Clean mushrooms and pat dry. Set aside. In a mixing bowl, add flour, garlic powder, onion powder, lemon pepper, ground mustard, egg, and beer. Whisk together ingredients until smooth. In a separate container, put bread crumbs and set aside. Preheat deep-fryer to 375 degrees. Place mushrooms in beer batter and cover thoroughly. Remove mushrooms from beer batter and place in container with bread crumbs. Cover thoroughly. Remove mushrooms from bread crumbs and place into deep-fryer. Cook for 5-7 minutes. Remove from deep-fryer and put in separate container. Season to taste with seasoning salt. For sauce..in an empty bowl add mayonnaise, horseradish, lemon pepper, lemon juice, onion powder, garlic powder and dill weed. Mix ingredients thoroughly. Add salt and pepper to taste.