Miso Broiled Black Cod, also called Alaskan Cod or Sablefish, has an unmatched melt-in-your mouth quality. It's buttery and flaky, and the delicate crust from broiling the fish, is sweet and savory. Served with fresh Bok Choy, you will not be able to get enough of this meal!
In a medium-sized mixing bowl, whisk the miso paste with the mirin, sake, wasabi, ginger, sugar and oil. Whisk until it's very smooth and the pour the mixture into a large zip-lock bag. Add the fish, remove all the air from the bag, and seal it. Make sure all of the fish is well-coated. To be sure it doesn't leak, put this bag in a second bag. Then place it in the refrigerator for at least 6 hours and ideally overnight.
About 15 minutes before you'd like to serve, slice the peppers into thin strips and the bottom inch or so off the bok choy and simply break it apart.
Remove the fish from the refrigerator, and cover a baking sheet with foil. Adjust the rack under the broiler so the fish will be a few inches from the flame (about 4), and turn it on. Remove the fish from the bag, letting any excess marinade drip off. Then place the fish on the foil-covered baking sheet. Place the baking sheet in the broiler until the fish has nicely caramelized on top, and is just barely cooked through (It should still be slightly transluscent in the center). It should take about 5 minutes. You can use a fork to check for doneness -- as soon as the fish flakes apart, it's done.
While the fish is cooking, coat a large sauté pan with grapeseed oil over medium heat. Add the bok choy, peppers and sesame seeds, and cook until the bok choy is wilted, about 3 minutes. Drizzle with the sesame oil and season to taste with salt and pepper. (Here's How to Season to Taste.)
Serve the fish alongside or on top of the vegetables.