Plate the schnitzel, season with salt and pepper. Turn in flour, then in beaten egg and then in breadcrumbs. Bake for 1-2 minutes on each side in a pan with hot fat, turning once. Then drain on paper towels.
Briefly toast the bread slices in the toaster.
Brush bread with butter, cover each with half a schnitzel that is still warm. Place onion rings seared in fat (or some red and white cabbage salad) on top. Place a fried egg on top.