Pat dry the chicken, inside and out, with kitchen paper.
In a small bowl, mix salt, sand ginger powder, white pepper, turmeric (if using), and cooking oil.
Rub the mixture over the chicken, including the cavity, making sure it’s evenly coated.
Leave to marinate for 4 hours or overnight in the fridge. Take it out 1 hour before cooking so it returns to room temperature.
Cook
Preheat the oven at 390°F/200°C/Gas 6 (Fan-assisted 360°F/180°C).
Insert scallions and ginger into the cavity of the marinated chicken, then place the chicken into an oven-proof pot fitted with a lid, or into a deep baking tray covered tightly with kitchen foil.
Place the pot/tray on the middle shelf and leave to cook in the oven for 1 hour.
Then leave to rest, without removing the lid/cover, for 30 minutes (see note 2).
Serve
Take the chicken out and keep the liquid gathered at the bottom of the pot.
Cut the chicken into small chunks to serve, or tear it into shreds.
Put chopped scallions and ginger paste into a small bowl. Mix in 2-3 tablespoons of the chicken juice (heat it briefly if it has gone cold).
Use the sauce for dipping, or pour it over the chicken.
Notes
1. Sand ginger tastes very different from regular ginger, so they’re not interchangeable. You can find sand ginger powder in Chinese/Asian stores.2. If you use a heavy cast iron pot that retains heat well, bring it out of the oven and let it rest on the counter. If using a regular baking tray covered with kitchen foil, leave it inside the oven to rest.