To make the glaze, combine all the ingredients in a medium saucepan and bring to a simmer over moderate heat. Reduce heat to low and cook 3 minutes, stirring occasionally. Set aside to cool.
Spread about a third of the glaze over the bottom of a glass baking dish just large enough to hold the fish in a single layer. Place the fish in the dish and spread the remaining glaze on top to coat them completely. Cover with plastic wrap and refrigerate overnight.
Make the dressing, slaw, & cook the fish
Make the miso dressing:
Peel and finely grate the ginger. Squeeze the grated ginger over a small bowl to yield about 2 tsp. ginger juice (discard the pulp). Add the miso, vinegar, sesame and canola oils, and sugar; whisk until the sugar dissolves. Refrigerate the dressing.
Make the asian slaw sauce:
In a small saucepan add 1 tablespoon olive oil, ginger and garlic, lightly saute until lightly brown. Add brown sugar, soy sauce, and mirin. Saute for 5 minutes and remove from heat. When cool whisk in olive oil, sesame oil and rice wine vinegar.
Cook the fish:
Prepare a grill or preheat the broiler. Scrape the glaze off the fish and discard. Pat the fish dry with paper towels and brush lightly with olive oil. Grill or broil 3 inches from the heat source 3 or 4 minutes. Turn and cook 2 to 3 minutes longer, or until cooked through.
Mix all the vegetables in a bowl and toss with the slaw sauce.
Spread some of the miso dressing on the bottom buns and top with fish.
Place some of the slaw over the fish and top with some of the fried wontons.
Alternatively you can skip the buns and place the fish over the slaw and drizzle some of the miso dressing over top.