This idea was given to me by the man who runs the fish market.  It makes a very impressive presentation.

Place large filet of grouper in oven proof dish.  Pour about ¼ inch white wine in pan.  Dot fish with butter and squeeze lemon over.
Make a mixture of:
Mayonnaise
Sour cream
Parmesan cheese
Finely chopped green onion

Spread mixture over fish and bake at 350 degrees 25 minutes.
Place under broiler and broil until bubbly.  Serve immediately.