Soak the lentils in cold water for 1 hour. Blanch the bacon in boiling water for 5 minutes. Drain and rinse with cold water. Melt the lard in a large saucepan and cook the onions and bacon until golden, about 5 minutes. Drain the lentils and add them to the saucepan, along with 6 cups of water, the bouquet garni, the tomatoes, garlic, and salt. Bring to a boil, then reduce heat to a simmer, cover, and cook for 40 minutes, adding a little more water if the lentils start to dry out. Season with freshly ground black pepper before serving.
