Combine the lentils, water, and bay leaf in a large heavy-bottomed saucepan and bring to a boil. Reduce heat, cover, and simmer 30 to 40 minutes, until the lentils are tender. Add salt to taste. Drain and retain some of the cooking liquid.
Heat the oil in a large heavy-bottomed skillet or casserole and add the onion and garlic. Saute over medium-low heat until the onion is tender and beginning to color. Add the green pepper and chili peppers and saute another 5-10 minutes until the pepper is tender and add the tomatoes and drained lentils.
Add a little bit of cooking liquid from the lentils if the mixture seems dry. Simmer over medium-low heat for 15 minutes. Season to taste with more salt and pepper, stir in the cilantro and lemon juice if desired, and serve, or allow to cool and serve chilled. This dish will keep for 3-5 days in the refrigerator. Serves 6-8.