For the best flavour, the pork belly needs a good long marinade. Combine the char siu and oyster sauces. Reserve some of the marinade in a little bowl for basting, then rub all over the pork belly. Cover and refrigerate overnight

To make the steamed buns activate the yeast in 100ml of warm water. Add this to the rest of the ingredients and knead until the dough is smooth – a few minutes. Allow to rest in a warm place covered with a damp cloth for 2 hours, or until doubled in size

Roll the dough into a cylinder then divide into 12 pieces. Roll each piece into an oval, brush lightly with flavourless oil, and fold in half. Allow to rest in a warm place under a damp cloth for 30 minutes, or until 1.5 times the size

Line a bamboo steamer with greaseproof paper and steam the bao for 8 minutes, making sure not to lift the lid during the first half of cooking time (you may need to do this in batches)

Preheat a barbecue for indirect cooking. Lift the belly slices out of the marinade and cook for around 20 minutes, turning once, or until they reach an internal temperature of around 60°C

Move them over to direct heat and baste with a little of the reserved marinade, then cook for a few minutes each side, or until golden and beginning to char in places. Keep basting with extra marinade as they are cooking for a delicious sticky finish. Set aside to rest

Rub the tomatoes and spring onions with a little neutral oil and grill over direct heat for a few minutes, until charred on all sides. Chop finely and combine with the soy sauce and rice vinegar

Crack the eggs into a bowl and season with salt and pepper. Melt the butter in a saucepan and add the eggs. Move them around gently with a wooden spoon over a low heat, letting them form natural waves as they move about. Don’t over-stir. When they look around 80% cooked, remove them from the heat and set aside

Now you have everything ready, it's time to assemble. Layer up the warm buns (if they have cooled after steaming, pop them back in the steamer for a few minutes until soft and warm) with some lettuce, egg, sliced pork and tomato sauce. Garnish with coriander, chilli oil and spring onion slices