Break 1/2 head of lettuce into a wide, shallow bowl or dish. Slice onions and celery (as much or as little as you wish) over top. Mix 1/2 C of sour cream with 1/4 C of powdered sugar. Drip over the top.
Break the remaining lettuce over the top. Mix 1/2 C mayonnaise with 3 T red wine vinegar. Drizzle over top.
Cover with crumbled bacon and lots of parmesan cheese. Refrigerate uncovered for 2 hours. Do NOT toss. When serving, make sure you dig deep to get the flavor of both layers. Enjoy.