If you don't have canned lentils on hand, you can cook them by combining 1 cup of dry lentils with 4 cups of water in a large pot. Bring the liquid to a boil, then lower the heat to a gentle simmer and cover to cook for 20 to 30 minutes, until the lentils are tender, but not mushy. Drain the lentils, and then they are ready to measure and use in this recipe.