Mirin Salmon

Mirin Salmon : 1/4 cup mirin (japanese sweet rice wine), 1/4 cup light brown sugar, 1/4 cup soy sauce, 4 (4 oz) pieces of salmon, preferably wild and cut from the thick part of the fillet so that they are narrow but tall rather than wide and flat), 2 tablespoons rice vinegar, 1/2 scallions, halved.