Cut the fish fillets into 3 in/7.5 cm pieces about 1 in/2.5 cm thick. Brush a frying pan with one tablespoon of olive oil and warm over very low heat. Arrange the fillets in the pan in a single layer, so they do not touch the sides.
Cover with a tight-fitting lid and cook over low heat until the flesh on the underside becomes opaque, about 10 minutes. Turn the