Grease a 9" baking dish and cover the bottom with thinly sliced onion. Break one matzo into sections and arrange over onions. Cover with slices of tomato, sprinkle with salt, pepper and sugar and top with sections of the second matzo. Cover with the remaining onion slices and top with the third matzo. Cover and bake 30 minutes at 350 f. Remove cover and if the top layer of matzo is not softened, add 1/2 cup of soup or water. Continue to bake until lightly browned on top.