Preheat the oven to 180°C.
Cut the spring onions into thin pieces. Slice the ginger and garlic.
Line a large roasting tin with a large piece of foil that is big enough to wrap the fish.Then line this with a large piece of untreated parchment paper.
Make 3 cuts on each side of the fish, then put them in the lined tin.
Put some garlic and ginger into the cuts and the cavity, together with some spring onion. Scatter the rest around the fish.
Mix the soy sauce, sesame oil and rice vinegar, then drizzle it over the fish. Fold the parchment paper over the fish, then wrap it with the foil, creating a well sealed packet.
Place the tin in the oven for about 25 minutes, until the fish is cooked through. Don’t overcook it!
Serve warm.