A local store has frozen vacuum-packed 4 oz fish fillets on sale for 50 cents. They are labeled "opah" but I don't know whether that's accurate. When defrosted, they have the consistency of a raw pork chop. After I fried one up, it had the consistency of a tough cooked pork chop. Is this very unusual? I'd describe the taste as mild.
How might I cook these fillets to make them less tough? Would simmering them in a miso broth work? How about grinding them up in a blender and forming patties to fry?