Photograph: Martin Poole
Preheat the oven to 190°C, fan 170°C, gas 5. In a bowl, mix together the chilli, ginger, lemongrass, coriander stalks, fish sauce and lime slices.
Arrange the fish in a shallow roasting tin, and slash the skin of each 3 times on each side. Stuff the chilli mixture in and around the cavity of each fish. Bake for 20-25 minutes.
Meanwhile, mix all the ingredients together for the dressing. Scatter the remaining chilli, coriander leaves, spring onion and toasted sesame seeds over the fish. Serve with lime wedges to squeeze over and the dressing on the side.
Get ahead: stuff the fish a few hours ahead; chill.