COOK FISH: Heat the oil, butter, and crushed red pepper in a medium flat heavy skillet over medium-high heat until butter is melted and bubbling. Salt and pepper both sides of the fish, patting spices in with your fingers, and add to the skillet an inch or two apart. Let cook 3 minutes until browned; turn and cook the other side, 2-3 more minutes. Lower heat to medium and cook another minute or two OR until fish is nearly firm, opaque, but still moist. (If your fillets are thin, it will take less time. If they're thick, you'll need a bit more time. Fish will continue to cook after taken off the heat, so less is better.)