Process chilli, ginger, lime leaves, garlic, shallot, lemongrass, coriander roots, oil and 2 tsp sea salt in a food processor to a paste. Rub inside the fish cavity and spread thickly over fish, massaging into incisions. Cover and marinate for at least three hours or overnight.
Preheat oven to 220°C or heat a hooded barbecue to high. Place fish on an oven tray lined with oiled foil and drizzle with a little extra oil. Roast until flesh flakes easily (45-50 minutes).
For pomelo and herb salad, pound chilli, garlic and palm sugar to a paste with a mortar and pestle. Stir in 1 tbsp hot water, then add lime juice and fish sauce – check seasoning and adjust the balance of hot, sour, sweet and salty to taste. Store in an airtight container until required. Just before serving, combine herbs, shallot and pomelo in a bowl, drizzle with dressing and toss to combine.
To serve, squeeze lime over snapper and scatter with salad.
