Lay out a large piece of aluminum foil. Slice the lemon and lay the slices inside the foil. Lay the filet of fish on top. Slice the butter and lay on top of the fish. Salt and pepper the fish. Bake at 300 degrees for 40 minutes or until done.
Recipe by Seeing Sunshine at https://seeingsunshine.com/2013/05/30/baked-grouper/