Red lentils soften into the broth rather than sitting in it as separate little beans. That makes them useful for a substantial soup without a blender, but it also explains why yesterday's leftovers can look almost solid.
For about three servings, soften a chopped onion and carrot in a tablespoon of oil. Stir in a teaspoon of ground cumin, then add 180 g rinsed red lentils, a 400 g tin of tomatoes, and 900 ml vegetable stock. Use a stock whose ingredients suit your diet.
Simmer for roughly 20–25 minutes, stirring occasionally, until the lentils have broken down and the carrot is tender. Add more water if needed. Finish with lemon juice, tasting a spoonful before seasoning the whole pot.
There is room for texture at the table: chopped herbs, a spoonful of plain unsweetened plant yogurt, or toasted bread. When reheating a safely chilled portion, add water gradually and stir until hot throughout.