Mix the cheese, crab, egg yolk, lemon, chopped ginger, and spring onion, then season.
Cut a slit in each fish piece and fill with the cheese mixture.
Blanch lettuce leaves in boiling water, chill in cold water, and wrap the fish into parcels.
Combine the fish stock, five spice, and balti paste in a shallow dish.
Place fish parcels in the stock, cover with foil, and bake at 190°C for 20-30 minutes.
Fry ginger matchsticks in butter until crisp and set aside.
Remove cooked fish parcels from the stock and keep them warm.
Boil the stock in a saucepan until reduced by half.
Whisk butter into the boiling stock until the sauce thickens and shines.
Serve parcels with sauce and topped with crispy ginger.