Preheat your broiler. Cut the bok choy heads and scallions in half, lengthwise. Whisk together the fish sauce, ½ tablespoon of vinegar, 1 tablespoon sesame oil and the sriracha. Taste and adjust seasoning with sea salt and pepper. Toss bok choy and scallions with sauce (reserve remaining dressing).
Whisk together miso or coconut aminos, 1 tablespoon rice vinegar, minced garlic, minced ginger and 1 tablespoon of maple syrup. Generously brush this glaze on the flesh side of the salmon. Lay fish, skin side down, on a lightly oiled baking sheet. Arrange scallions and bok choy, around the salmon. Broil until the fish begins to flake, about 8 minutes. Remove salmon from sheet and continue to broil veggies for another 2-5 minutes.
Arrange on a plate, drizzle with remaining dressing and sprinkle with sesame seeds.