In the pot, add the reserved bacon fat and melt the remaining 2 tablespoons of butter. Add the onion and garlic and cook over moderate heat, stirring occasionally, until softened, 5 to 7 minutes. Add the tomatoes, crushed red pepper, a generous pinch of salt and one 28-ounce can of water (about 3 cups). Bring the soup to a boil over high heat, breaking up the tomatoes with the back of a spoon, then reduce the heat to moderately low and simmer until thickened slightly, 15 to 20 minutes. Stir in the honey.