Finely chop the water chestnuts, garlic, ginger, coriander and 2 out of the 3 spring onions and place in a large mixing bowl. Next add the minced beef and egg yolk to the mix and stir together well. In a pan over a medium high heat, toast your cumin seeds until fragrant (30 seconds–1 minute) before tipping into a mortar and gently crushing using a pestle. Once crushed, add the seeds along with the other ‘Marinade’ ingredients into the filling mix, and stir to combine well.

Using a free-standing mixer with a dough hook attachment (if available), pour in the measured out 'Dry Mix' ingredients.

Mix 'The Liquid' ingredients together into a measuring jug. Then slowly pour the liquid into the mixer while kneading on a low speed for around 2 minutes until all the water is mixed into the flour. Once combined, turn the speed up to high speed for a further 2 minutes until the dough has a smooth-yet-tacky feel to it.

Once the dough has been well kneaded, dust with 2 tbsp of flour, scraping off any additional dough on the sides of the bowl. Shape the dough into a rough ball, and then coat lightly with 1 tbsp of vegetable oil, cover the bowl with a damp cloth and leave aside in a warm, preferably moist, draft free location (like inside a room temperature oven) for 1–1.5 hours.

Once the dough has doubled in size, place the dough onto a well-floured work surface and, using a rolling pin, start to roll it out until it is approx. ½ cm in thickness. Finely chop the last spring onion and scatter the pieces over the freshly rolled out dough. Using a cookie cutter (or the lip of a glass if necessary) approx. 7cm in diameter, cut the dough into as many pieces as possible. Then follow the instructions below to construct and fill your bao:

1. Place 1 ½ tsp of filling into the centre of the pastry
2. Lift up the pastry and squeeze the edges together as if forming a drawstring money bag shape with your dominant hand
3. Holding the pastry in your dominant hand, twist the top of the pastry tightly and continuously with your non-dominant hand, ensuring the filling does not leak out, until the pastry is completely sealed and you have a slightly swirled, spiralled effect at the top, and a well-rounded dumpling below.
4. Once well sealed, make sure the bao resembles an even ball shape by lightly rolling and adjusting it, then set aside on a well floured tray, and cover it with a slightly damp clean cloth or tea towel to keep it from drying out.
5. Continue to roll and fill the baos until either all the filling or dough has been used up
6. Allow the uncooked baos to rest for a further 15–20 minutes in a warm, draft free humid place, such as a room temperature oven.

Fill a wok ⅓– ½ way with boiling water. Line 2 bamboo steam baskets with dim sum steam paper or pierced greaseproof paper. Brush the paper with a little vegetable oil and then place the prepared baos into the steam baskets, twisted side down (to prevent any loose ends from opening up). Cover the baskets with a lid and steam on high for 8 minutes, resisting the temptation to open the lid at all during this time.