heat sake and mirin in a pan over medium heat
turn down heat and add miso and whisk to dissolve
add granulated sugar and whisk to dissolve
let marinade cool to room temperature
place marinade in baking dish and add black cod
toss to coat fish then cover and refrigerate overnight
preheat oven to 400
Line a baking sheet with foil and spray with oil or use parchment paper to line sheet with no oil
add grapeseed oil or any neutral oil to a frying pan to coat pan and place over high heat
scrape marinade off of cod and add to hot pan skin side up
cook for 3 minutes then turn fillets and cook for another 3 minutes
place on foil lined baking sheet and place in oven until fish is cooked through. About 10 minutes.