If you're using jarred lentils, skip ahead to the "Tomato Sauce and Simmering" step
Rinse the lentils, then place them in a pot with three times their volume of unsalted water.
Bring to a boil, then cook for 25 minutes, until the lentils are tender and the cooking liquid has been absorbed.
Tomato sauce and slow cooking
Peel and slice the onions and celery into rounds. Sauté them over low heat in a saucepan with a little olive oil for 5 to 10 minutes. A reminder for beginners: never let the onions burn; always cook them covered, over low heat, and check on them from time to time!
Once the onions are translucent, add the tomato purée and the lentils. If you have any herbs—such as thyme, bay leaves, or sage—now is the time to add them. They’ll give your tomato sauce even more flavor!
Season with salt and pepper to taste, then cover and let all the ingredients simmer over low heat for at least 5 minutes…and there you go—it's ready! Easy, right?!
Notes
SERVING SUGGESTION: Serve these lentils with rice for a complete, protein-rich meal. Grains help the body absorb the protein found in legumes, and the combination of rice and lentils is particularly popular among vegetarians.