Position oven rack 6 inches from broiler and heat broiler.
STEP 2
In small microwave-safe bowl, whisk together honey, soy sauce, and balsamic vinegar. Microwave until slightly thickened, 60 to 90 seconds.
STEP 3
Pat cod fillets dry and season with salt and pepper. Spoon half of the glaze over cod and brush to coat. Broil until cod is opaque throughout, 6 to 7 minutes. Spoon remaining glaze over the top.
STEP 4
Meanwhile, heat oil in a large skillet over medium-high. Add garlic, scallions, chile, and ginger and cook, tossing for 30 seconds. Add bok choy and salt. Cover and cook for 2 minutes. Uncover and cook, tossing, until bok choy is tender, 3 to 4 minutes more (adding water if necessary). Serve with glazed cod and sprinkle sesame seeds on fish if desired.