Brush liver with soy sauce. Arrange with thickest pieces to outsied in 23 cm pie plate. Spoon onions evenly over liver. Cover tightly and microwave on high (100%) 3 minutes; turn pie plate one-half turn. Microwave until liver is no longer pink, 1 to 3 minutes (do not overcook). Let stand 3 minutes. (Liver will continue to cook while standing.) Sprinkle with lemon juice and parsley just before serving.