Lentil Soup Recipe UK: A Cosy, Easy British Classic

This UK-style lentil soup is a comforting, thick red lentil soup made with carrots, onion, celery, warming spices and vegetable stock. It is straightforward to cook on the hob, uses everyday ingredients and makes a satisfying lunch or light supper; versions vary, but this one balances gentle cumin and coriander with a bright squeeze of lemon.

Ingredients

1 tablespoon olive or rapeseed oil (15 ml)
1 medium onion, finely chopped (about 1 cup / 150 g)
2 medium carrots, peeled if desired and diced (about 1½ cups / 160 g)
2 celery stalks, diced (about 1 cup / 100 g)
2 garlic cloves, finely chopped (about 2 teaspoons / 6 g)
1 teaspoon ground cumin (2 g)
1 teaspoon ground coriander (2 g)
½ teaspoon smoked paprika (1 g)
1 cup split red lentils (190 g), picked over and rinsed
5 cups vegetable stock (1.2 L), preferably low-salt
1⅔ cups chopped tomatoes (400 g)
¾ teaspoon fine salt (about 4 g), plus more to taste
¼ teaspoon ground black pepper (about 0.5 g), plus more to taste
1 tablespoon lemon juice (15 ml)
2 tablespoons chopped fresh parsley (about 8 g), to serve

Measurements use US cups and spoons; a US cup is about 240 ml. Red lentils are sold split and usually cook down into a soft, thick soup. Vegetable stock keeps this version meat-free; if using a salty stock, start with less added salt and adjust at the end.

Instructions

Prepare the vegetables and lentils. Finely chop the onion, dice the carrots and celery, and chop the garlic. Rinse the red lentils in a sieve under cold water, moving them around with your fingers, until the water runs mostly clear. Check quickly for any small stones or debris, then let the lentils drain while you start the vegetables.
Soften the vegetables. Set a large, heavy-based saucepan over a medium heat and add the oil. When it is warm, add the onion, carrots and celery. Cook for 8 minutes, stirring regularly, until the onion looks translucent and the carrots begin to soften. Keep the heat moderate: the vegetables should soften rather than brown deeply, which can give the soup a bitter edge.
Wake up the spices. Stir in the garlic, cumin, coriander and smoked paprika. Cook for 1 minute, stirring so the garlic does not catch on the bottom of the pan. The spices should smell fragrant. If the pan seems dry, add a small splash of stock rather than extra oil.
Add the lentils and liquid. Tip in the rinsed lentils, vegetable stock and chopped tomatoes. Add the measured salt and black pepper, then stir thoroughly, scraping the bottom of the pan to loosen any vegetables or spices. Bring the mixture up to a gentle boil; this usually takes a few minutes.
Simmer until tender. Lower the heat so the soup bubbles gently, then partially cover the pan with a lid. Simmer for 25 minutes, stirring every 5 minutes or so, especially across the base of the saucepan. The lentils should be very soft and beginning to break apart, and the diced carrots should be tender when pierced with a fork. If the mixture catches, lower the heat and add a little water.
Choose the texture. For a rustic soup with some texture, use a wooden spoon to break up a few of the softened lentils against the side of the pan. For a smoother finish, blend with an immersion blender until it reaches the consistency you like. If using a countertop blender, let the soup cool slightly, blend in small batches, and avoid filling the jug to the top; hot liquid expands and can force the lid off.
Finish and taste. Stir in the lemon juice and taste a spoonful once it has cooled enough to judge. Add more salt, pepper or lemon a little at a time. If the soup is thicker than you want, stir in hot water or stock until it is easy to ladle. If it is too thin, simmer it uncovered for a few minutes, stirring often.
Serve. Ladle into warm bowls and scatter over the chopped parsley. A little extra black pepper or a drizzle of olive oil is optional. Serve while hot, with bread or another accompaniment if you like.

Tips

Rinse, but do not soak. Split red lentils do not need soaking for this recipe. Rinsing removes dust and helps the soup cook evenly; soaking can make them soften sooner and may leave you with a thicker result than expected.
Control the thickness with liquid. Red lentils absorb stock as they cook and the soup thickens further as it stands. Keep some hot water or stock nearby, and add it gradually at the end rather than making the soup watery at the start.
Watch the pan once the lentils are in. Lentils settle and can stick to the base if the heat is too high or the soup is left unstirred. Use a gentle simmer, stir down to the bottom periodically, and add a splash of liquid if needed.
Adapt the seasoning to your stock. Stock cubes and ready-made stocks can vary a lot in saltiness. Beginning with low-salt stock and adding salt after cooking gives you more control. Lemon also lifts the flavour, so taste before adding extra salt.

Serving Suggestions

Serve this soup in bowls with crusty bread, a bread roll or warm flatbread for dipping. For a simple meal, add a green salad dressed with lemon or vinegar; its crispness contrasts well with the soft, hearty soup. A spoonful of plain yoghurt can make each serving creamy and cool, while a little chopped parsley or coriander adds freshness. For a dairy-free bowl, use a swirl of olive oil instead.

The soup is filling enough to serve as a main course for lunch or supper, but smaller portions also work as a starter. If you are serving several people, put the toppings on the table separately so everyone can choose. Offer lemon wedges for anyone who wants a sharper finish, and keep bread separate until serving so it stays crisp.

Variations

Make it warmer: Add ¼ teaspoon chilli flakes (about 0.5 g) with the spices, or serve chilli oil at the table. Increase cautiously, since heat builds as the soup simmers. For a more ginger-forward flavour, add 1 teaspoon freshly grated ginger (about 5 g) when you add the garlic.

Use different lentils: Brown or green lentils can replace red lentils, but they hold their shape more and take longer to become tender. Use about 1 cup (190 g) and simmer until soft, checking the packet guidance; add extra stock if needed. The finished soup will be less smooth and may need a longer cooking time than the 25 minutes given here.

Add greens: Stir in 2 packed cups of chopped spinach (about 60 g) during the last 2 minutes of simmering, or add 1 cup (about 70 g) of finely sliced kale for the final 5 to 8 minutes, until tender. These additions bring a fresher, greener flavour and can make the soup thicker, so loosen it with stock if necessary.

Make it creamier: Blend all or part of the cooked soup, or stir in ½ cup (120 ml) coconut milk at the end. Coconut milk adds a mild sweetness and a distinct flavour, while blending alone keeps the original seasoning more prominent. You can also add a peeled, diced potato with the carrots for a more substantial, naturally thicker soup.

Storage and Reheating

Cool leftovers promptly and refrigerate them within 2 hours of cooking, in a covered container. The soup keeps for 3 to 4 days in the refrigerator. It thickens as it chills, so stir in a splash of water or stock when you warm it. For longer storage, freeze in meal-sized portions for up to 3 months; leave a little space at the top of each container for expansion. Defrost overnight in the refrigerator for more even reheating, or reheat from frozen over a low heat with a little extra liquid.

Reheat only the portion you plan to eat, stirring frequently on the hob until steaming hot throughout. In a microwave, cover loosely, heat in short intervals and stir between each one so there are no cool spots. For food safety, leftovers should reach 165°F (74°C), the USDA FSIS reheating recommendation; check the centre with a food thermometer if you need to verify the temperature. Do not leave reheated soup sitting at room temperature for an extended time.

Frequently Asked Questions

Can I make this lentil soup without a blender?

Yes. Red lentils naturally soften and break down during simmering, so the soup is thick even without blending. Mash a few lentils and vegetables against the side of the pan with a spoon for a slightly smoother texture while keeping some pieces intact.

Why is my lentil soup too thick?

Red lentils absorb liquid as they cook, and the soup continues to thicken as it cools. Stir in hot water or stock a little at a time until it reaches the consistency you want. Taste again after thinning, since the added liquid can dilute the seasoning.

Can I use tinned lentils instead of dried red lentils?

You can, but the result will be different because tinned lentils are already cooked and usually stay more intact. Drain and rinse about 2 cups (roughly 400 g) of tinned lentils, reduce the stock to around 4 cups (950 ml), and simmer the soup until the vegetables are tender. It will not become as naturally smooth as the dried red lentil version.

Can I prepare the soup ahead?

Yes. Make it fully, cool it promptly and refrigerate it in a covered container, following the storage times above. The flavours settle as it rests, and the soup will be thicker the next day. Add water or stock as it reheats and finish with a little lemon juice if the flavour needs refreshing.

Is this recipe suitable for a vegetarian or vegan meal?

It is suitable for a vegetarian meal when made with vegetable stock. For a vegan version, check that the stock contains no animal-derived ingredients and choose plant-based toppings such as olive oil, parsley or crusty bread without dairy. The soup itself contains no meat, eggs or dairy.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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