Put the lentils in a strainer and pick through them, discarding any bits of stone that might have escaped the packers; rinse under cold running water.
Put lentils in medium sauce pan.
Press the clove into the onion and toss the onion, carrot, celery, garlic, and bay leaf into the pan. Pour in the broth or water, stir in the lentils, and bring to a boil. Lower the heat to a steady simmer and cook for 25 to 30 minutes, or until the lentils are almost tender. As the lentils cook, skim off the solids that rise to the top and stir as needed. Season with salt and pepper and cook until they’re tender, another 5 to 10 minutes.
Drain the lentils, reserving the cooking liquid if you’re going to want to reheat them. Remove the vegetables and either discard them all or discard the clove, thyme, and bay leaf.
The lentils are ready to be served now, set aside and reheated over low heat in the liquid you’ve reserved, or used in other recipes.