Squeeze excess liquid from spinach; set aside. In a mixing bowl combine the eggs, cheese, bread crumbs, vinegar, salt, and black pepper. Stir in the well-drained spinach. Pat mixture into a greased 8x4x2-inch loaf pan. (At this point, loaf may be covered and refrigerated overnight before baking.)
Bake, uncovered, in a 400 degree F oven for 20 to 25 minutes or until a knife inserted in the center comes out clean.
Meanwhile, in a medium skillet cook bacon until crisp. Remove from skillet, reserving 2 teaspoons of the drippings. Drain bacon on paper towels. Cook onion and sweet pepper in hot drippings over medium heat for 5 minutes or until tender. Stir in the flour and black pepper. Gradually stir in water. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. Stir in bacon and tomatoes; heat through. To serve, invert loaf onto platter. Cut loaf into slices; serve with sauce. Makes 8 servings.