Position Oven Rack: Adjust an oven rack so it sits approximately 6 inches below the heating element. This ensures the salmon cooks through without the glaze scorching too quickly.
Formulate the Glaze: In a small mixing bowl, combine the white miso paste, tamari, rice vinegar, maple syrup, toasted sesame oil, and grated ginger. Whisk vigorously until the mixture is smooth and emulsified.
Preheat the Broiler: Turn your oven’s broiler function to HIGH, allowing it to preheat for at least 5 minutes. A fully heated broiler is key to achieving a beautiful, caramelized crust.
Season the Salmon: Pat the salmon fillets completely dry with a paper towel. Arrange them in the oven-safe skillet, leaving space between each fillet. Spoon about two-thirds of the prepared glaze evenly over the top surfaces of the fish.
First Broil: Carefully place the skillet on the prepared oven rack under the hot broiler. Cook for 4 to 6 minutes. The initial broil cooks the salmon most of the way through.
Final Glaze & Finish: Remove the skillet from the oven. Brush the remaining glaze over the fillets. Return the skillet to the broiler for an additional 1 to 2 minutes, just until the glaze is bubbling and the fish is opaque throughout. The salmon is done when it flakes easily with a fork or reaches an internal temperature of 145°F (63°C).
Garnish and Serve: Let the salmon rest for a minute in the skillet. Garnish with a sprinkle of toasted sesame seeds and fresh green onions before serving immediately.