Marinate the fish steaks in lime juice for 30 minutes. Heat 3 tablespoons of the olive oil in a frying pan and sauté the fish steaks until fully cooked, about 5 minutes on each side. Remove fish steaks from the frying pan and set aside.
Heat the remaining oil in a separate pan and sauté the garlic, onions and tomatoes, until tender. Stir in the fish sauce and w