Heat the oil in a large nonstick skillet over medium-high heat. When the oil is hot but not smoking, add the fillets. If it is necessary to do this in two batches, use the same oil. Saute on one side until golden brown, about 3 minutes. Turn and cook on the other side until golden brown, about 3 minutes more. When the fillets are done, transfer them to a warm platter or serving plate.