In a large pot, heat oil over high heat.
Add onion and garlic, and sauté until golden.
Stir in tomato paste, cumin, salt, black pepper and chilli flakes, and sauté for 2 minutes.
Add stock, water, lentils and carrot.
Bring to a simmer, then partially cover pot and turn heat to medium-low.
Simmer until lentils are soft (about 30 mins)
Season to taste.
Purée half the soup in a blender then return it to the pot.
Reheat if necessary.
Stir in lemon juice and coriander.
Suitable to freeze (before adding lemon and coriander)
3 tablespoons olive oil
1 large onion, chopped
2 garlic cloves, minced
1 tablespoon tomato paste
1 teaspoon ground cumin
¼ teaspoon salt, more to taste
¼ teaspoon ground black pepper
Pinch of dried chilli flakes, more to taste
1 litre chicken or vegetable stock
2 cups water
1 cup red lentils
1 large carrot, peeled and diced
Juice of 1/2 lemon, more to taste
3 tablespoons chopped fresh coriander