Take Halibut pieces and place them in a rectangular baking dish with enough white wine to cover half the fish. Cover and allow to marinade for several hours. (If you take your Halibut out of the freezer in the morning you can place it in the marinade right away till you are ready to cook.) You can’t over marinate the fish.
In a mixing bowl combine the sour cream and mayonnaise, (depending on taste, you can also substitute yogurt.) Dice onion,and place in the sour cream mixture. Mix together. Make sure the onion is finely chopped or it will overwhelm your sauce.Some people like more sour cream than mayo, I like it the other way around. More mayo makes the sauce more savory.
Take the marinated Halibut pieces and pat each piece dry. Then roll each piece through plain breadcrumbs, I like finely chopped parsley, it adds something to the flavor of your breadcrumbs. Pour melted butter in bottom of glass baking pan. I think it adds flavor to your fish. Place each breaded piece of Halibut side by side in baking dish. Cover evenly with the sour cream/mayo mixture. Sprinkle with paprika, this is an essential part of the recipe, so don't forget it.
Place in a preheated 425’ oven. Cook till the Caddy Ganty is bubbling and slightly gold in appearance. About 15 to 20 minutes unless you have a very hot oven. Serve over hot white rice and the flavor will knock you out!