Halibut is the largest of the flatfishes — a giant, cold-water bottom-dweller of the northern oceans (Atlantic halibut, Hippoglossus hippoglossus, and its Pacific cousin Hippoglossus stenolepis) prized for thick, snow-white, lean and remarkably firm flesh. Mild and gently sweet with a clean marine note, it cuts into dense steaks and fat fillets that hold their shape on the grill and flake into large, meaty leaves — the premium white fish of Alaska, Norway and the North Atlantic.