Preheat oven to 375. Sprinkle chicken with garlic salt to taste. Mix together melted margarine or butter, paprika and lemon juice. Brush chicken well with butter mixture and place in shallow baking pan. Bake, tented with foil, about 30 minutes or until tender, brushing with remaining butter mixture occasionally to keep from drying. In a bowl, blend together sour cream, sherry or broth, mushrooms, and pepper. Pour over chicken for last 15 minutes.