Salt and pepper the salmon.
In a small bowl add the miso paste, soy sauce, brown sugar, rice vinegar, and sesame oil. Wisk together until smooth. Reserve 1 tablespoon of marinade.
In a medium sized bowl add the salmon and the sauce. Let it marinade for 1-3 hours.
Preheat oven to 375 degrees. In a large skillet add the salmon and discard marinade. Bake for 12-15 minutes, or until fish is almost done and opaque. Brush with reserved glaze and Broil on high for 1-2 minutes until fish reaches 125-130 degrees in the center.
Garnish with green onions and sesame seeds if desired.