Whisk white miso, sugar, sake, mirin, and soy sauce in a bowl.
Rub sea bream with vegetable oil and coat with the miso mixture.
Marinate the covered fish in the fridge for two hours.
Remove fish from marinade and place skin-side up on a clean surface.
Thread metal skewers diagonally through fillets, folding them into ripples.
Repeat skewering on the other side of the fillets and add lemon wedges to ends.
Preheat grill to highest setting and grill fish skin-side up for 5 minutes.
Turn fillets over and grill for another 5 minutes until fully cooked.
Remove lemons and slide each fillet onto a serving plate.
Boil green beans in salted water for 30 seconds, then drain and ice.
Boil rice vinegar and caster sugar in a clean pan.
Pour hot vinegar over sliced onions and chilli; pickle for 30 minutes.
Mix tomatoes, beans, pickled onions, chives, and some pickling liquid.
Season salsa with salt and pepper and serve alongside the fish.