If using canned mushrooms, squeeze all liquid from mushrooms first. If using fresh, do not rinse, wipe clean instead.
Mix pancake flour, garlic powder, salt and pepper in a bowl or plastic baggie. (Plastic bag is best.) Coat livers in pancake mixture, coating thoroughly. Set aside on paper plate.
Heat 2 Tb margarine or oil in a frying pan and saut onions until just clear. Remove onions and set aside.
In a clean pan, heat 1/4 cup margarine or 3-4 Tb. oil on a medium to high heat. Place livers in pan side by side one at a time. As soon as edges start to brown turn livers over one at a time, put onions and mushrooms into pan and lower heat. If necessary add more margarine by adding small amounts around the edge so as not cool down pan. Saut slowly and tenderly for another 2 or 3 minutes on a medium heat or until done.
Remove from heat and serve immediately with a rice pilaf or alone as an appetizer.