Bring the saké and the mirin to a boil in a saucepan on high. Boil for 20 seconds to evaporate the alcohol.
Turn the heat down to low and add the miso paste. When the miso has dissolved completely, turn the heat up to high again and add the sugar. Stir constantly to ensure that the bottom of the pan doesn’t burn, and the sugar is completely dissolved.
Remove from heat and cool to room temperature. Refrigerate.
Suggested marinating times for seafood and meats: Fish - 2 to 3 days; Shrimp and Scallop - 4 hours; Chicken - 1 day, overnight; Beef - 1 day, overnight
Notes
Recipe adapted from Nobu Matsuhisa.
Recipe by Bebe Love Okazu at https://bebeloveokazu.com/2012/09/10/miso-marinade/