How to make onion rings:
Peel and cut the onion into two halves. (Keeping the rings…) Fry them for roughly 30 minutes, until tender, then pry the rings apart.

Mix the fish, crab and shallot in a food processor for 30 seconds. Stir the water, egg, coriander, and
1/2 ts salt in the mixture by hand. Season with
pepper. Heat the soybean oil, try to fry one fish
ball first. Season some more if necessary.

Arrange the fish balls and onion rings in layers. Sprinkle with sweet and sour sauce and garnish with lettuce.