Move the pan under the broiler on high for three to five minutes until some brown starts to form on the top. Using a towel or oven mitt to hold the pan, return the pan to the burner over medium heat and add miso, rice vinegar, sugar, soy sauce, garlic and ginger. Bring to a simmer and baste the salmon. Cook the salmon until the ends are slightly firm to the touch, and the center has a slight give. Remove the salmon and place it onto your plate. Keep reducing the sauce until it is slightly thicker than maple syrup. Taste and season with more soy (needs salt), sugar (too acidic or salty), and water (too thick or sweet), as needed. Spoon some sauce over each piece of salmon and serve.