In a small bowl, add plum wine, honey, soy sauce, vinegar, miso paste, garlic and ginger. Whisk the ingredients until well mixed and the miso paste is dissolved.
Place salmon fillets in a wide rimmed serving dish and pour the marinade over. Cover with plastic wrap and refrigerate for 2 to 4 hours.
In small skillet over medium heat, toast the sesame seeds, tossing them occasionally until golden brown, about 4 to 5 minutes.
Remove from the heat and transfer them to a small bowl to cool off.
A few hours later, transfer the salmon fillets on a baking sheet lined with foil that has been lightly greased with cooking spray. Let the fillets sit for about 15 minutes to warm up near room temperature.
Pour the marinade in a small saucepan and set the burner between medium and medium-low. Simmer until it reduces and thickens.
Transfer the fillets under the broiler – about 6-inches from the element – and set the timer for 7 minutes or until nicely charred and caramelized.
Carefully remove the fillets from the heat, pour the sauce over, sprinkle on sesame seeds and green onions; serve immediately.