1. Heat a medium frying pan on a medium high heat. Add a little oil, season the fish with salt and cook for 3-5 minutes on each side, or until the fish is cooked to your liking.
2. While the fish is cooking, halve both avocados and discard the seeds. Scoop out the avocado flesh and place in a medium bowl. If there are any brownish bits, remove them.
3. Mash avocado with a fork and stir in the juice of one lime. Season with salt and taste. Add more lime juice and salt as needed, and then stir in the green onion (if using).
4. If using lettuce, wash and break into individual leaves. If using tortillas, wrap and warm them in the oven
5. To serve divide fish between 2 plates.
6. Pop avocado mix into two small bowls and give one per person.
7. Serve lettuce leaves or tortillas in the middle and let each person make their own wraps.