Combine miso and next 3 ingredients in a large glass baking dish. Add fish, spooning glaze over all sides. Cover and refrigerate 2 to 4 hours.
Place fillets on a foil-lined baking sheet, and broil, about 6 to 8 inches from heat, 8 to 10 minutes or until fillets are golden brown and center of fish is opaque.
Spoon warm Coconut Broth into shallow bowls, and place fillet in center. Garnish, if desired. Serve immediately.