Sprinkle liver with salt and pepper; dredge in flour, and set aside.
Cook bacon in a heavy skillet until crisp; remove bacon, reserving 2 tablespoons pan drippings in skillet. Drain bacon on paper towels; set aside.
Cook liver in pan drippings over medium heat until browned on both sides; top with onion slices. Cover and simmer 20 minutes or until liver is no longer pink.
Transfer liver and onion slices to a warm serving platter; garnish with reserved bacon and parsley sprigs. Serve immediately.