Use the lentil that fits the texture
Rinse the red lentils in a sieve until the water runs less cloudy. Look through them for small stones or debris before they go in the pot. Keep an extra cup of water nearby during cooking; the soup thickens as the lentils absorb liquid.
Build the base without rushing the onion
A soft onion and carrot make the soup taste rounded before the tomatoes arrive. Cut the carrot into small pieces so it finishes with the lentils. If it remains in large chunks, the lentils can turn soft while the carrot is still noticeably firm.
Tomato paste needs a minute against the warm vegetables. Stir until it darkens slightly and stops smelling sharply raw. Add the cumin during that minute, then pour in the tomatoes and stock before anything begins to catch on the bottom.
Keep the simmer gentle and stir underneath
As the lentils soften, the bottom of the pot can thicken ahead of the surface. Run the spoon along the bottom every few minutes, particularly near the end. A vigorous boil makes more mess without making the soup easier to manage.
Start checking at twenty minutes. The lentils should be soft enough to crush easily, with no firm center. If they need longer, add water and continue simmering. Old lentils can take extra time, so leave some room in the schedule.
Finish the bowl after tasting the pot
Lemon juice wakes up a thick soup, but canned tomatoes already bring acidity. Add a teaspoon, taste, and continue only if the soup needs it. If it tastes too sharp, a spoonful of yogurt in the bowl may give you the balance you want.
Serve with warm bread and chopped parsley. Yogurt belongs on top, where its coolness meets the hot soup, rather than boiled into the pot. When reheating, add a little water first and stir often; lentils continue to thicken the broth as it sits.
