Pre Heat oven to 350 F. Place the salmon, bok choy and optional mushrooms on a parchment lined (or foil lined) baking sheet.
Mix marinade ingredients (soy, mirin, sesame oil, honey and ginger) together in a small bowl and spoon it over the fish and veggies, coating all sides well.
Sprinkle the salmon with a pinch of salt and pepper and a little fresh orange zest, then place the sheet pan in the oven, checking it after 10 minutes. Depending on how thick or thin the salmon is, it may be done, or need a few more minutes- so remove it if need be- thinner cuts will cook faster. At this point, you could broil the fish and bok choy, giving the bok choy a little toss first – or simply continue baking a few more minutes, until the bok choy is just tender ( yet green and vibrant and crisp).
Divide among 2 bowls. Sprinkle each bowl with toasted sesame seeds, scallions, and chili flakes or sriracha for heat.