Heat 1 tablespoon of the oil in a wok over a moderate heat. Add the egg mixture and swirl so it spreads thinly over the surface of the pan. Let it set for about 30 seconds, then loosen the edges with a fish slice and flip over. Cook for 10 seconds, remove to a chopping board, roll up and slice into ribbons. Set aside.
Add 4 tablespoons oil and, once it begins to shimmer, stir-fry the shallots for 4–5 minutes until golden and crisp. Remove with a slotted spoon and drain on kitchen paper. Set aside.
Drain all but 1 tablespoon of the oil from the pan. Add the onion and stir-fry until beginning to brown. Add the garlic, black bean sauce, rice wine, chilli and Chinese five-spice powder and stir-fry for 2 minutes.
Add the stock, noodles and bean sprouts and bring to the boil, tossing the noodles and bean sprouts in the stock.
Add the pork to the wok with the green vegetables, prawns and salt and cook for a further 4 minutes. Top with the deep-fried shallots, shredded omelette, sliced chillies and coriander leaves and serve with sweet chilli sauce.