Pour the warm milk into a small bowl along with 2 tbsp of the sugar - stir together until dissolved. Sprinkle over the yeast. Whisk lightly and leave to go slightly foamy.
Place the remaining ingredients in the bowl of a stand mixer fitted with the dough hook attachment. Knead for a minute or until you have a very sticky messy dough. Remove the dough hook and cover the bowl - leave for 10 minutes for the dough to hydrate fully. After 10 minutes return the hook to the stand mixer and knead for around 5 minutes or until you have a smooth ball of dough.
Cover the bowl with a damp cloth and place in a cold oven. Pour around 100ml boiling water into a baking tray and place at the bottom of the oven - beneath the dough. Leave until doubled in size (around 1-2 hours).
While the dough proves, whip up your Scallion Glaze by combining the scallions, sea salt, sugar and sesame oil in a small bowl. Set aside.
Once proved, remove the dough from the oven and push out any large air bubbles with your finger tips. Lightly flour a work surface and tip the dough out onto it. Divide the dough in half with a sharp knife then divide each half into four. Form each piece of dough into a small ball and place on a baking tray. Cover with cling film and leave to relax for 10 minutes.
Once the dough is relaxed, remove one ball from the tray and place on the floured surface, covering the rest of the balls back up. Dust the top of the ball and, using a rolling pin, roll out into a long oval. With a very sharp knife or pizza cutter, cut strips into the dough along the length of the oval, leaving a 1/2cm at the top and bottom of the dough (as in this video). Brush the cut dough with your scallion glaze.
Pinching both ends of the oval, twist them in opposite directions )as though you’re making a cheese strauntil you have a very twisted piece of dough with scallions showing through the layers. Curl the length of dough around like a snail and then tuck the loose end over and under (or, again, just copy this video). Place on a square of baking parchment before repeating with the other balls of dough.
Once all the balls of dough have been transformed into twisted buns, place them on a baking tray and cover with cling film. Return them to your oven (again, not switched on and add a little more boiling water to the a tray in the bottom of the oven to help them prove. Leave to prove for 35 minutes.
Once proved, turn on a steamer or place a bamboo steamer over a pan of boiling water. Place the buns in the steamer with plenty of space around them (they’ll grow quite a lot as they cook). You may have to cook them in 2 batches. If you do, place the buns which aren’t cooking in the fridge to stop them from overproving. Steam your buns for 13 minutes.
While they’re steaming, mix together all the dipping sauce ingredients in a small bowl.
Once steamed, they should be nicely puffed up. Allow them to cool slightly before serving with a small bowl of dipping sauce and a sprinkle of fresh scallions!