Heat 1 tablespoon of butter in a large saucepan over medium heat.
Cook and stir onion until brown or caramelized, about 6- to 8 minutes and cool down.
Mix mayonnaise, mustard, dill weed, sour cream, lemon juice, Worcestershire sauce, Tabasco sauce, and when all together add salt & pepper to taste and set aside.
Mix bread crumbs, shredded parmesan, chopped parsley, paprika and melted butter and set aside.
Cut halibut into 5- or 6-ounce fillet, layer caramelized onion on a baking dish pan.
Place cut halibut on top of onions and then coat it with mayonnaise mix and sprinkle with bread-crumb mix.
Bake at 350 degrees in a conventional oven for 10- to 12 minutes or until meat is flaky and serve.
