Mix miso, mirin, ginger, and orange juice together.
Rub vegetable oil over skin of salmon.
Season skin with salt and pepper.
Spoon marinade over fillet, coating the side of the fillet as well.
Allow to marinate for 30 minutes to 24 hours in the chiller.
Preheat oven to 190C.
When oven is ready, remove most of the marinade on top of the fillet.
Miso burns easily, removing it ensures that we won't get a charred piece of fish.
Bake it on the top rack for 10-12 mins, until fish flakes easily.
(+/- 10 mins for each inch in thickness).