Step 1 Rinse the lentils and place in a medium, heavy-bottomed pot. Add the carrot, onion, garlic, thyme, olive oil, salt and water, and bring to a boil. Reduce the heat to a very gentle simmer, skim any scum floating on top and loosely cover. Continue to cook until the lentils are tender, 20 to 25 minutes. Remove from heat and pull out the carrot, onion, garlic and thyme. Strain the lentils, reserving 4 cups of the lentil stock and 2 cups of the cooked lentils (any leftover stock and lentils can be used for another purpose). If you are short the 4 cups stock, add enough water to make 4 cups.