To make the dumplings, mix all the ingredients together in a bowl. Spoon a tablespoon of filling into the middle of each wrapper. Crimp, seal and place on a plate line with baking paper. Place in the fridge, uncovered for 1 hour.
To make the Sichuan chilli oil, mix the cumin, chilli powder, Sichuan pepper, 2 tablespoons of gochugaru, Chinese five spice and sesame seeds together in a large heatproof bowl. Place a sieve over the bowl and set aside.
Gently heat the oil, ginger, star anise, bay leaves and remaining 3 tablespoons of gochugaru in a saucepan until bubbling and the ginger us beginning to brown at the edges.
Pour the oil through the sieve set over the spice mix while still hot. Discard the contents of the sieve and set the spiced oil aside to cool. Once cooled, store in the fridge.
To make the black vinegar mayonnaise, mix the ingredients together in a bowl.
To serve, heat a little oil in a lidded frying pan and fry the dumplings for 1 minute. Add 200ml/7fl oz water, cover and steam the dumplings for 3 minutes.
Divide the dumplings between plates and briefly fry the curry leaves. Top each plate of dumplings with some chilli, curry leaves, coriander leaves, a spoonful of black vinegar mayonnaise and a drizzle of chilli oil.