Fit piecrust into a 9-inch pieplate according to package directions; fold edges under, and crimp.
Line piecrust with aluminum foil, and fill with pie weights or dried beans.
Bake at 350° for 5 minutes; remove foil with weights, and bake 4 to 5 more minutes.
Arrange tomato in piecrust, sprinkling each layer evenly with sugar, salt, and pepper. Sprinkle top evenly with flour.
Stir together mayonnaise and cheese; spread evenly over tomato.
Bake at 350° for 30 minutes.
