-
Preheat the oven to 450°F. In a small saucepan, whisk together the tamari, mirin, 1 tablespoon of the vinegar, the sesame oil, brown sugar, ginger, garlic, and cornstarch. Cook over medium-high heat until the mixture is thick and syrupy, 6 to 8 minutes. Set aside.
-
Meanwhile, slice the mushrooms in thick strips, leaving small mushrooms whole. In a large bowl, toss the mushrooms and the bok choy with the grapeseed oil, the remaining 2 tablespoons vinegar, 1⁄2 teaspoon salt, and a few grinds of pepper.
-
Scatter the mushrooms and bok choy in one layer onto two rimmed baking sheets. Nestle the salmon fillets alongside the vegetables on the pans. Spoon some of the mirin glaze over each salmon fillet.
-
Roast, turning the vegetables halfway through, until the salmon is opaque and the vegetables are crispy and golden brown, about 15 minutes. Transfer each fillet to a dinner plate, spoon more glaze onto each salmon piece, and garnish with the green onions. Divide the roasted vegetables among the plates and serve.