Lentil and Bean Stew with Gremolata

Lentils add a delicious earthy flavor to the stew; their starchiness helps thicken the broth. Brown lentils work fine in this recipe, but we prefer French green lentils; they hold their shape better. Feel free to cook dried beans especially for this recipe, but any leftover or canned beans—rinsed and drained—will work well.