Add the oil to a 5cm depth in a large pot and heat to 170C.
For the CHILLI SAUCE, add all the ingredients to a saucepan and simmer for 1-2 minutes, until the sauce thickens slightly. Pour into a serving bowl.
Whisk the egg whites in a large bowl until foaming. Whisk in 200 millilitres of iced water; sift in Vegeta Chicken Stock Powder , rice flour, potato starch, plain flour, soda, ground pepper, Chinese five spice and and mix with chopsticks until roughly combined, leaving it slightly lumpy.
Dust chicken pieces in extra rice flour and add to the batter; fold until well coated
Fry chicken in batches for 6 minutes each. Drain on paper towel and set aside, keeping the batches separate.
Once the chicken has all been cooked, fry again for another 3-4 minutes, starting with the first batch you cooked, until deeply golden. Drain again and transfer to a warm plate.
Sprinkle with sesame seeds and spring onion, serve immediately with the chilli sauce.
Sweet rice flour also called glutinous rice flour is available from Asian food stores.