Skin ring bologna.
Place in 2-quart casserole.
Cut into 8 pieces, retaining ring shape.
Slice potatoes into 1/4-inch slices.
Place half the potatoes over bologna.
Sprinkle with chopped onion.
Add the remainder of potatoes.
Top with cream of mushroom soup.
MICROWAVE 4 MINUTES on HIGH, then MICROWAVE 8 MINUTES on '6'.