Combine the 2/3 cup mirin, 1 cup low sodium soy sauce, 2 tablespoons rice vinegar, 1 teaspoon sesame oil, 1/3 cup light brown sugar, grated or minced 4 cloves fresh garlic and grated or minced 2 tablespoons fresh ginger in a small saucepan. Bring the mixture to a low boil, then simmer for 10-15 minutes. Mixture will be thin and boil over easily due to the sugar, so keep the heat low and watch carefully.
Using an immersion blender or small food processor, blend well.
In a separate bowl or small measuring cup, whisk together the 3 tablespoons cornstarch or arrowroot and 3 tablespoons water until fully combined. Mix with teriyaki marinade until it becomes glossy. Remove from heat, mixture will thicken as it cools.
Salmon:
Preheat the oven to 350°F and line a baking sheet with parchment paper.
Place the 12 ounces salmon, cut into 4 equal filets, on the prepared baking sheet and season liberally with 1/2 teaspoon coarse sea salt and 1/2 teaspoon ground black pepper .
Bake for 10 minutes. Remove and baste with the prepared teriyaki sauce, return to the oven for 5 minutes.
Remove and baste again, returning for 2 minutes.
Remove and top with the 1 tablespoon toasted sesame seeds and sliced 2 tablespoons scallions.
If you've tried this recipe, come back and let us know how it was in the comments or star ratings.
Notes
Cooking times can vary greatly depending on the size and thickness of your salmon. Check internal temperature for a minimum of 120°F.