This vegetarian lentil soup with lemon and rosemary is a soup powerhouse! It's healthy, can be cooked in the slow cooker (crockpot) or on the stove in a dutch oven and is so easy to make. What is more it is low carb and naturally gluten free.
The lemon and rosemary gives it a freshness, whilst the blended red lentils and vegetables give it a rich creamy texture without the need for cream. Perfect for fall; serve this soup for lunch or dinner and don't forget the bread and butter. Unless you are serving it up to your vegan friends, then skip the butter!
How to make Red Lentil Soup with Lemon
To make this easy soup:
- first sauté off onions, carrots and celery.
- add red lentils, rosemary and vegetable broth.
- cook long and slow to allow the lentils to break down.
- blend your soup (optional step)
- add fresh lemon and more rosemary to boost the flavor.
Can I use my slow cooker/crockpot to make lemon lentil soup?
Yes yes yes!
I mean is there anything more comforting that coming home to a slow cooker full of delicious warming soup? I have given instructions for both stove top and slow cooker cooking.
Do I need to cook my onions before adding them to the slow cooker?
If you have time then I recommend you sauté the vegetables before you put them in the slow cooker (in fact some slow cookers have a sauté option). It adds so much more flavour to the soup. I know it dirties an extra pan, but when you are eating soup for dinner you want it to be the best soup it can be. 😀
Is this Lentil Soup with Lemon and Rosemary healthy?
It sure is!!! And that is what we want to hear! I mean everyone loves a bowl of healthy lentil soup cooked in the slow cooker!
A nice large bowl of this soup will only cost you 278 calories and because of the lentils this is a really filling soup.
I can't guarantee that the bread and butter on the side is healthy though 😉
What about dietary restrictions?
Is this Lentil Soup gluten free?
100% yes! There are no thickening agents in this lentil soup, the red lentils and vegetables do all the work for you so that makes this naturally gluten free!
Is this Red Lentil Soup vegan?
It is sure is! Everything is plant based in this soup, making it perfect for vegetarians and vegans. Just be sure to check your stock. I specify vegetable broth in the recipe and whilst I have never seen a vegetable broth that isn't vegan you just never know. Especially when you thinks that they sometimes use fish to clarify wine (yes really!!!)...you have to wonder about other seemingly vegan ingredients. So to be sure just check your broth is vegan.
Can the lentil soup be frozen?
This soup freezes extremely well and tastes just as good when it is defrosted. A few tips for freezing your soup:
- Allow the soup to fully cool before placing it in the freezer.
- Portion your soup out before you freeze this. It will defrost more quickly and you won't waste any. (I like to use ziplock bags, but tupperware contains are just as good (and they stack!)
- If using a container don't overfill it. Water expands as it freezes so make sure you allow some room for this expansion.
- Make sure you label your bags/containers. Once frozen this is almost impossible to distinguish from chicken and lentil stew or frozen gravy. And you don't want to get the wrong one out for dinner!
I don't want to freeze it, but how long will the lentil soup keep in the fridge?
This lentil soup tastes even better the following day! But I wouldn't keep it more than 3 days in the refrigerator. And as with all leftovers ensure it is piping hot before you serve it.
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Red Lentil Soup with Rosemary and Lemon
- 2 onion
- 2 carrots
- 2 cloves garlic
- 2 stalks of celery
- 1 tbsp olive oil
- 2 cup red lentils
- 3 tsp chopped fresh rosemary - divided (see note 1)
- 8 cups vegetable broth
- ½ tsp salt
- ¼ tsp pepper
- 1 lemon
- Peel and finely chop the onions, carrots and garlic.
- Wash the celery stalks and cut them in half lengthways. Then chop the long sticks into small dice.
For the slow cooker
- Optional stage (see note 2)Pour the olive oil into a large fry pan and once hot, sauté your onions over a medium heat for 3-4 minutes until softened and starting to lightly colour. Add in your carrots and celery garlic and cook for a further 3 minutes. Stir in the garlic and cook for another minute.
- Add the vegetables, red lentils, 2 tsp of the fresh rosemary and vegetable broth to the slow cooker and cook on low for 7 hours or high for 4 hours.
- Give your soup a vigorous stir to create a creamy texture and then add in the seasonings, the zest of the lemon and the additional teaspoon of fresh rosemary.
- You can blend it at this stage if you wish.
- Serve immediately or set to keep warm.
To cook on the stove.
- Pour the olive oil into a large stock pot and once hot, reduce the heat and sauté your onions over a medium heat for 3-4 minutes until softened and starting to lightly colour.
- Add in your carrots and celery garlic and cook for a further 3 minutes.
- Stir in the garlic and cook for another minute.
- Add the red lentils to the pan along with 2 tsp of the fresh rosemary and vegetable broth.
- Cook over a low heat for 40 minutes until everything has softened.
- Give the soup a stir every now and then and once it has finished cooking stir it vigorously to give your soup a creamy texture.
- You can blend it at this stage if you wish.
- Finish the soup with the seasonings, the zest of the lemon and the remaining fresh rosemary.
- Fresh rosemary really is king here, but if you only have dried add just 2 tsp of dried to the soup before you cook it and then skip the rosemary garnish.
- Although sautéing the vegetables before putting them into the slow cooker means dirtying another pan, the flavor it gives your soup is so worth it. But if you are short on time this step is optional.