1. Start broiler, set at Moderate, 350° F. Grease the rack in a broiler pan.
2. Have the liver cut in slices uniformly thick, 1/2 inch or a little less. Remove membrane and wipe with a clean, damp cloth. Have the flour spread on a plate, dip each slice in it.
3. Place on the greased broiler rack and put in the broiling oven 2 inches from the heat. Broil 2 1/2 to 5 minutes on each side. Remove to a warmed platter, pour the butter over the pieces, sprinkle with salt and pepper.