Heat oven to 400 degrees and grease a 10 inch pie pan. Cook hamburger with onion, drain grease. Add salt and pepper, spread in pie plate. Melt margarine, mix with flour, milk, and eggs (make sure mixture is smooth). Pour onto hamburger in pie pan. Bake 25 minutes at 400 degrees. Remove from oven, top with sliced tomatoes, sprinkle with cheese. Bake another five to eight minutes, until cheese is melted. Cool five minutes before eating. Variations: shred carrot and/or zucchini and add to batter. Eliminate hamburger, use beans instead, or in addition to hamburger.