Marinade: In a cup, combine miso paste, sake, mirin, and sugar. Whisk well until completely dissolved and there are no lumps.
Fish: Pat dry the fish and slice it into 4 equal pieces.
Marinate the fish: In a rectangular food storage container with lid, pour-in ⅓ amount of the marinade. Place the fish filets in with skin side up then pour-in the remaining marinade. Seal the container and refrigerate to marinade for at least 6 hours or up to 24 hours in advance.
Prepare sheet pan: Line a baking sheet pan with parchment paper or foil. Lightly spray the oil over so that the fish won’t stick to the pan. You can also use a non-stick silicone baking mat like I do.
Wipe off the excess completely: Use your hands to wipe away the marinade on both sides and as much as you can so that the fish is less likely to have burn spots. Place the fish skin-side down (or smoother side down if skinless) in a single layer on the mat.
Broil: Let the broiler heat up for 5 minutes. Place the sheet pan in the center of the oven and 8 inches (20 cm) away from the heat source. Boril for 8 to 10 minutes. Check after 8 minutes. Important! Fish cooked very quickly in a broiler. 1 minute can make a difference so watch it carefully. If your fish is thinner than 1-inch, reduce the broil time by 1-2 minutes.
Temperature test: The fish is cooked when you can flake it easily and the top portion is light dark golden brown because of the marinade. Slight charred spots are okay. Insert a digital thermometer at an angle at the thickest part and it should reach 145°F (62.78 °C). If not, send it back for 1 minute and check again.
Transfer: The fish out of the oven and let the fish rest for a few minutes until they are no longer piping hot. Carefully and slowly use a fish spatula to scoop out the fish. They will be very buttery soft so be gentle.
Serve: Transfer to a serving plate. Remove pin bones, if any. Serve with skin on or off with a side salad and rice on the side. Serve immediately.
Video
Notes
For reference my total broiling time was 9 minutes. I checked the temperature after 8 minutes and the fish needed another 60 to 70 seconds to bring it up to the safe temperature.
Substitute: If sablefish isn’t available, sea bass or halibut are great options. They’re mild, tender, and pair beautifully with miso marinades.
Broiling basics: When broiling, you don’t adjust the oven temperature like you would when baking or roasting. Instead, the trick is to control how close the food is to the broiler. The closer it is, the faster and more intense the heat, which is perfect for creating that golden top. For something delicate like cod, you’ll want just the right distance to cook it evenly without burning.
Why Wipe Off the Excess Marinade? Removing the excess marinade is important because the sugars in the miso, sake, and mirin can easily burn under high heat, especially during broiling. By wiping it off, you reduce the chances of burn spots while still keeping the flavor locked into the fish. It also helps the fish cook more evenly and develop a nice caramelized surface without sticking or charring too quickly.
Make Ahead: You can prepare the marinade (miso, mirin, sake, sugar) up to 2-3 days ahead and store it in the fridge. Marinate the fish for at least 6 hours or up to 24 hours before cooking. For longer storage, freeze the fish in the marinade for up to 2-3 weeks, then thaw overnight in the fridge when ready to cook.
Post-cooking storage: Leftovers: After cooking, store any leftover miso cod in an airtight container in the refrigerator. It's best consumed within 2 to 3 days. To reheat, gently warm it in the oven at a low temperature to maintain its tender texture.