Clean the cavity of the fish and trim the fins to prevent burning. Place the spring onions and ginger in the cavity.
Grill the fish on a rack over coals or bake on a rack over a roasting pan at moderate heat. Total cooking time should be approximately 15 minutes.
Turn after 7 minutes and test with a wooden skewer to see if it's done at the thickest part near the head. The flesh should be opaque and flake easily.
Arrange the spinach and lettuce leaves on a serving platter. Fan out the sliced cucumber on the platter and decorate with celery, sprigs of herbs and chillies.
Blend all the ingredients and place in small bowls.
Remove the fish from the rack and place on a board or plate. Scrape away scales and skin. Turn and repeat process.
Transfer to serving plate, season and serve.
At the table, remove fish from the bone with 2 forks, wrap it in spinach or lettuce leaves with a selection of herbs and vegetables, and dip in sauce before eating.