Heat oil in a wok, add in pork fat and fry until crispy then remove from wok with perforated ladle. Leave the oil in the wok. Add in garlic and fry for 2030 seconds. When lightly golden add prawns and fish cake. Fry for a while.
Put in noodles. Fry well to combine. Add in water and seasoning ingredients. Stir-fry to combine. Add the mustard green. Cover the wok and cook for 12 minutes. Remove the cover and add the pork fat crisps, then dish out and serve immediately.