Preheat the oven to 200°C.
Cut 3 or 4 diagonal slashes on either side of the snapper, then lay it on a large piece of baking foil in a roasting tin.
Peel and finely chop the garlic & ginger then rub all over the fish and into the cuts.
Lift the sides of the foil around the fish then pour the combined sauce ingredients over it. Scrunch the foil together to create a parcel then put in the oven for 30-35 minutes.
Meanwhile, slice the spring onions into slivers and roughly break the coriander.
Heat the groundnut oil until just smoking in a pan. Carefully take the snapper out of its parcel (leaving the juices) and put on a serving dish. Immediately pour over the hot oil to crisp up the skin, followed by the sauce from the parcel.
Garnish with the spring onions and coriander. Serve with jasmine rice and pak choi.