Remove wingtips with a sharp knife, then halve wings at joints. Combine in a non-reactive bowl with fish sauce, cover and refrigerate for flavours to develop (1-2 hours).
Combine fried shallot and 1 tbsp sea salt in a small bowl and set aside. Combine vinegar and sugar in a separate small bowl, stir to dissolve and set aside.
Heat oil in a deep-fryer or deep-sided saucepan to 180C. Dust chicken wings in seasoned flour, shake off excess, and deep-fry, in batches, until golden (2-3 minutes; be careful as hot oil may spit). Remove with a slotted spoon, drain on absorbent paper, scatter with shallot salt and serve hot with vinegar dipping sauce.
Note Fried shallots are available from Asian