Finely chop the onion and garlic. Pour a generous dash of oil to cover the bottom of a saucepan, add the chopped onion and garlic to soften on a low heat for about ten minutes. If they start to sauté, add a tablespoon of water. Add the already cooked lentils to the pan, then add the peeled tomatoes and the bay leaf, and let the mixture cook for two or three minutes, then add water (about a litre), salt, and cook for about 20 minutes. Excellent with fried or baked croutons.