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Easy Scottish Fridge Lentil Soup with Leftover Veg

A traditional and frugal Scottish Lentil soup made with red lentils and leftover vegetables. Great for using up what you have in the fridge and pantry.

Scottish Fridge Lentil Soup

Easy Scottish Fridge Lentil Soup with Leftover Veg

Doesn't it look gorgeous?

Fridge lentil soup, the best you've ever tasted and the perfect soup for the colder months.

Lentil soup makes a regular appearance on our table. 

I love the flavour and how warming and filling it is. 

So, you are probably wondering what's different about this fridge lentil soup? 

Well, you probably guessed it is all about using up leftover vegetables.

My fridge lentil soup is made from celery, carrots and a red pepper that all needed using up and fast, but you can use whatever veg you have.

Root vegetables work particularly well.

Easy Scottish Lentil Soup

Scottish Lentil Soup

Lentil soup is a traditional soup in Scottish homes.

Much of the year is cold and wet in Scotland, so hearty soups are always popular

We also love a frugal meal. Some call us tight but we are just careful with our money and like to use local and seasonal produce, which is always at its best and cheaper.

Buying in season means saving money as it's local and not flown halfway around the world.

We love hearty soups and lentil soup has always been popular as it is cheap, filling and nutritious as well as tasting great.

A large pot of red lentil and vegetable soup bubbling away, just perfect.

I hope you try this red lentil soup recipe.

What is fridge soup?

Fridge soup is all about using up what you already have in the fridge.

It's about using up those last bits of vegetables before your next shop, so you don't have any waste.

It's also a hearty lentil soup you can prepare with whatever you have, so no need to plan and pick up specific ingredients.

Stone Soup

Fridge soup reminds me of that tale of a travelling fox who stops at a farm and asks the animals if they can spare some food.

The animals say no, so the fox makes a big fuss over making a pot of stone soup. He spends a bit of time to find the right stone, then he adds water.

He tricks the animals who are all intrigued, to each bring a vegetable to make the soup taste even better and in the end, it's a proper pot of soup all the animals can enjoy.

Fridge soup is a bit like that, you use whatever you have and it feels like you are making a pot of soup out of almost nothing. 

When it's ready, it's a hearty meal the whole family can enjoy!

For more Scottish recipes have a look at my recipe index of Scottish Recipes for Vegans and Vegetarians

Scottish Fridge Lentil Soup


Cooking Lentil Soup in a pot

I usually make this soup in a pot (or dutch oven) on my gas hob, but you can make it in a slow cooker or an instant pot.

To cook this traditional Scottish lentil soup in a pot on your cooker top, saute the onion and garlic, then add the vegetables and cook gently for a few minutes.

Next, add the lentils and stock and cook for 30 minutes until the lentils are soft and the vegetables are tender.

Season and serve.

Making Fridge Lentil Soup in a Slow Cooker

This homemade lentil soup can also be made in a slow cooker or crockpot.

To make it in a slow cooker, you can either throw all the ingredients in and set the slow cooker, or saute the onion and garlic first, then add this mixture and all the other ingredients before hitting the start button.

Cook in the slow cooker on low for 8 hours or high for 6 hours.

Remember the rule of thumb when converting a recipe from hob to slow cooker is to reduce the liquid (stock) by a third.

Making Easy Red Lentil Soup in an Instant Pot

To make this lentil soup in an instant pot, select saute and let the pot heat, then saute the onion and garlic, before adding the vegetables, lentils and stock.

Make sure the release valve is in the sealing position, click the lid on tight and lock.

Set to manual and choose 10 minutes. 

Scottish Fridge Lentil Soup Ingredients - onion, garlic, celery, red pepper, carrots and red lentils


Here are the simple ingredients in my fridge lentil soup. Yours could be a little different.

  1. Olive oil - or rapeseed oil
  2. Onion - brown or red
  3. Celery
  4. Garlic - fresh or garlic powder
  5. Carrots
  6. Red pepper - because I had one that needed to be used up
  7. Red lentils - you could use split green or yellow lentils, but they can take a bit longer to cook
  8. Ground cumin - you can vary your spices, but do add some as they are warmth to the soup
  9. Ground coriander
  10. Vegetable stock
  11. Salt and black pepper - to season
Your fridge soup could be very different. 

The basics are still there, you want to start with onion and garlic, although you can swap the onion with leeks or spring onions if that's what you have.

And use whatever vegetables you have in your fridge or freezer.

Red lentils or yellow or green split lentils make the best fridge lentil soup as they thicken it and as they break down they make a thick vegetable broth.

Carrot tips

When I make easy lentil soup I add chopped and grated carrots.

In fact, I usually add some grated carrot to any soup I make with carrots.

Apart from less chopping which is always a good thing, the grated carrot almost melts into the soup and helps to thicken it.

Try it next time you add carrots to a soup.

What veg can you add to fridge soup?

Here are some of the vegetables you can include in a leftover lentil soup.

  • Aubergine - eggplant
  • Bell peppers - red, orange or yellow
  • Broccoli
  • Butternut squash
  • Carrots
  • Cauliflower
  • Celery
  • Courgette - zucchini
  • Leeks
  • Onion - red or brown
  • Parsnips
  • Potatoes
  • Spring onions - scallions
  • Sweet potatoes
  • Turnip - swedes

Use Leftover Vegetables or Cheap Vegetables

Look at what you have in your pantry fridge and freezer to make this soup.

If you're out shopping at your local supermarket or grocery store, pick up some cheap seasonal vegetables or any that have been reduced to sell fast.

When buying that marked down veg either make soup with it quite soon or freeze it to make the best lentil soup another day.

These are all good ways to save money.

uncooked red lentils in a bowl.

What are the best type of lentils to add to soup?

Here are a few types of lentils you can add to soup and the benefits of each.

Red lentils are one of the best lentils to use in soup as they can be added without any prep and they break down to a mush while they cook to give you a creamy soup.

Yellow lentils and split peas will also break down and make a soup creamy in the same way red lentils do, but they take longer to cook.

Brown lentils, green lentils and puy lentils are all good in soups too, but won't make a soup thick and creamy as they hold their shape. 

Puy lentils are also called French lentils.

Lentils are a good addition to soup as they are a good source of plant-based protein.

Why are lentils so good for you?

Lentils are a really cheap and healthy option. 

They are full of protein (which is important in a vegetarian diet or vegan diet), they are ; low in calories and rich in iron and folate.

They are easy and quick to cook with no preparation other than a quick wash.

Chunky or smooth lentil soup

I love a chunky lentil soup, but smooth soup is good too.

It's really a personal choice.

If you prefer a smooth soup, use a stick blender (immersion blender) to whizz it smooth in the pot.

However, if you are blending it in a food processor or blender, although it to cool first.

Better to be safe than sorry!

Close up of Scottish Fridge Lentil Soup

How long will lentil soup last?

This easy recipe makes the best lentil soup and it lasts a few days (unless you have a big family).

Allow it to cool to room temperature, then you can pour it into an airtight container and pop it in the fridge for 3-4 days.

Reheat in a pot or the microwave.

It will taste even better the longer it sits.

Can lentil soup be frozen?

Yes, leftover lentil soup can be frozen. It freezes really well.

Cool this delicious soup then freeze it in single-serving portions in freezer-safe containers or freezer bags so it is easy to take out just what you need.

If you freeze it in freezer bags, you can freeze it flat on a tray and stack the portions up to use up less space.

If you are trying to cut down on your plastic use, you can buy reusable freezer bags which are dishwasher and freezer-safe.

Just remember to label your portions with the name of the soup and the date you are freezing it.

This soup can be frozen for 3-4 months.

Take a portion out of the freezer the night before you need it and leave it in the fridge to defrost overnight, ready to be reheated the next day.

More Lentil Soups

Here are a few more lentil soups you may like to try after this easy soup recipe.

Other red lentil recipes to try

Here are some more lentil recipes to try next.

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Scottish Fridge Lentil Soup. A traditional Scottish soup made with red lentils. This is a low calorie, low fat and easy soup which is good if you are on a budget or calorie counting to lose weight. A filling meal for families that can be frozen. #Scottishlentilsoup #lentilsoup #scottishsoup #lefoversoup #redlentils #fridgesoup #redlentilrecipes #vegansoup

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Remember and say hi. I'm always happy to chat and answer questions.

Money saving budget soup

I costed this recipe with supermarket ingredients (at the time of publishing).

It costs £2.08 for the whole pot of soup, only 35p per serving (6 servings).

Look out for special offers, use frozen veg or buy in bulk to make this even cheaper per serving.

1 tbsp olive oil = 5p
1 onion = 10p
2 cloves garlic = 6p
4 carrots = 24p
2 red peppers = 30p
400g red lentils (21.4p per 100g) = 86p
2 tsp dried cumin = 24p
1 tsp dried coriander = 14p
3 stock cubes (value range 3p each) = 9p

Total = £2.08

soup, lentil soup, fridge lentil soup, fridge soup, Scottish soup, Scottish lentil soup
Yield: 6 - 8
Author: Jacqueline Meldrum
Easy Scottish Fridge Lentil Soup with Leftover Veg

Easy Scottish Fridge Lentil Soup with Leftover Veg

A traditional and frugal Scottish Lentil soup made with red lentils and leftover vegetables. Great for using up what you have in the fridge and pantry.
Prep time: 10 MinCook time: 40 MinTotal time: 50 Min


  • 1 tablespoon olive oil
  • 1 onion, chopped
  • 2 stalks celery, sliced
  • 2 cloves garlic, crushed
  • 4 large carrots, chopped
  • 3 large carrots, grated
  • 1 red pepper, chopped
  • 400g (2 cups) red lentils, washed well
  • 2 teaspoons ground cumin
  • 1 teaspoon ground coriander
  • 2 litres (3 ½ pints / 8.5 cups) vegetable stock, more if needed
  • a good grinding of salt and pepper


  1. In a large pot saute the onion, celery and garlic in the olive oil until the onion is soft and translucent.
  2. Add the chopped carrots and red pepper and cook gently for 5 minutes.
  3. Add the grated carrots, washed lentils and spices. Stir well, then add the stock.
  4. Bring to the boil, then reduce to a simmer, pop a lid on the pot and cook for 30 minutes until the vegetables are all tender and the lentils are soft.
  5. Season with salt and pepper.
  6. Serve with crusty bread.
  7. Enjoy!


  • This soup can be made in a slow cooker. Reduce the liquid by a third and cook on high for 6 hours or low for 8 hours.
  • This soup can be made in an instant pot. Set to manual and cook for 10 minutes.
  • Once cool, keep it in the fridge for 3-4 days.
  • This soup can be frozen for 3-4 months.
  • You can also use whatever vegetables you have in the fridge and freezer.


6 portions = 326 calories per portion

6 portions = 280 calories per portion

6 portions = 245 calories per portion

Nutrition Facts



Fat (grams)

2.67 g

Sat. Fat (grams)

0.37 g

Carbs (grams)

42.35 g

Fiber (grams)

17.89 g

Net carbs

24.45 g

Sugar (grams)

7.46 g

Protein (grams)

14.02 g

Sodium (milligrams)

1074.22 mg

Cholesterol (grams)

0 mg


  1. Lovely looking soup Jac and a change of style in your photos too - liking new rustic feel! Karen

    1. Thanks Karen, It's my new board that changes the look.

  2. I too love lentils, they're always in my cupboars. My OH Mum made me once the best lentil stew I've ever had - with loads of cumin, celery sticks and carrots, yum!

    1. Ohhhhhhhm sounds good Sylvia. You'll have to ask her for the recipe.

  3. This looks gorge Jac - the kind of soup that fills you up for the afternoon, which is exactly what I need to keep my fingers out of the cookie jar!

    1. Well yes, there is that, it is lovely and filling.

  4. Lovely, warming, thick deliciousness. You are making me very hungry.

  5. it looks delicious. I have a fridge soup planned to make this evening so may throw some lentils in too. Perfect to make it a more filling meal

    1. Adding lentils does make it a full meal and a great way of using up vegetables.

  6. Your soup looks amazing & I'm and hour and 15 minutes from lunch! I love your white pot also, it's beautiful! Have a lovely weekend!

    1. I love my pot too, Its a pro cook cast iron pot.

  7. Lovely, I have all those ingredients to hand and stuff to use up too, nice addition of spices. I'd just have to elave out the red peppers - allergic!

    1. I've not heard of anyone who was allergic to peppers before. That is a shame. Mind you I only added it as it was getting a bit soft. It will still be great without it.

  8. Ah lentil soup, the ultimate comfort food!

  9. Mmmmmmmmm! That is all :)
    Janie x

    1. Thanks Janie. It seems we are both in the mood for soup just now. I loved your watercress and pine nut soup,

  10. Ooooh I have a few veggies that are trying to make a bid for freedom from my fridge, Lentil soup for lunch tomorrow for sure. Great recipe.

    1. Ah well it is definitely time for soup then Lorna :)

  11. As I have a tub of cooked lentils left over in my fridge I will make the soup the other way around. Great idea, adore lentil soups and this looks so good too.

    1. Still a great idea Madeleine. Enjoy your soup :)

  12. the soup looks utterly sumptious Jac, love that you have red pepper in there too x

    1. Well it was sitting in the fridge looking sorry for itself, so what could I do :)

  13. Ooh this looks relish - I'm well into my lentils at the minute so will def try this. Something to do with the HOOOGE bag I bought from Costco!

    1. Haha, I am thinking you were going for delish there, unless relish is some new cool phrase. Thank you anyway :)

  14. ha, definitely my kind of soup. I think celery and carrot makes an excellent base for many soup recipes - especially veggie ones - creates a lovely flavour!!

    1. It is an essential base in my opinion, although I would add garlic to that list too.

  15. Love lentils and nearly always flavour them with cumin. Your soup looks delicious. We tend to make soup with whatever we have lying around.

    1. Cumin just works so well with red lentils, you can't go wrong. And yes fridge soups are the best.

  16. I could happily eat lentil soup every day along with lentil dal. I just need to convert my kids to loving them as much as I do!

    1. Cooper likes them, alhough he went off dal for a while and doesn't scoff it like he used too. Children are so funny with their likes and dislikes.

  17. Love it Jac. I often turn to lentils when I am in a rush and not sure what to make. They never fail to please.

  18. Love lentil soup - a firm favourite! Never used spices in it though, will have to experiment! xxx

    1. Oh yes you must. It tastes extra delicious when you add spices. So warming.

  19. Looks delicious - I love the taste of coriander!

    1. Me too, it's such a flavourful herb. I usually use fresh coriander, but dried works well in soups and dals.

  20. Lovely soup Jac! I love that little pottery bowl too!

    1. It's a bonnie wee bowl, isn't it? Can't remember where I got it though. I only have one though.

  21. Just made some very nice with the cumin and coriander ,excellent idea thanks

  22. I love red lentils in soup but always make the same recipe - yours looks and sounds lush so thank you for giving me another one to try:-) Hope you're good haven't seen you around much on twitter - I'm sure you're really busy!!

    1. Lentils are fab! No I haven't been on much, or on here even. Very busy a the moment. Weekends away, decorating and in-laws over from Cyprus, before all that lot we were poorly, so I am really out of the loop.

  23. Sometimes, those meals where you use up loads of leftover fridge ingredients are the best meals!

  24. beautiful pics - we are having quite a lot of lentil soup lately - it is so delicious - and a great way to clean out the fridge - I like how you chop some carrots and grate others - must try that - I have been doing a great job of using up vegies lately in soup, nut roast and even pasta dishes - feels so good to get the fridge under control except I found tonight I hardly had any veg left for sylvia

  25. Just made this soup, using, exactly what you said, soft, week old vegetables from my vegetable bin. My husband told me it tastes just like his mum used to make ( incidentally, he is also from Scotland, I am not ) and that does not surprise me as she was a frugal woman and would use up everything she had available!

    1. Well I can't expect for a better compliment than that. I hope you enjoyed it too Donna and thanks for taking the time to stop by. Much appreciated :)


I love reading comments, so thank you for taking the time to leave one. Unfortunately, I'm bombarded with spam, so I've turned on comment moderation. I'll publish your comments as soon as I can and respond to them. Don't panic, they will disappear when you hit publish. Jac x