Thaw fish and blueberries, if frozen. For blueberry sauce, cook and stir onion and garlic in a small saucepan in hot oil about 3 minutes or until softened. Add the blueberries, vinegar, brown sugar, ginger, and lemon peel. Bring to boiling; reduce heat. Simmer, uncovered, about 15 minutes or until sauce has thickened and reduced to 1 cup.