Makes 4 servings
Rinse and pat the dry fillets. Cut the tops of the green onions crosswise into 2-inch sections, then cut each piece lengthwise into thin strips; reserve for garnish. Thinly slice the white part of green onions. In a small bowl, mix soy sauce, mirin and rice vinegar. Preheat oven to 425°F (alternately, start grill). From a roll of foil, cut four 15-inch by 12-inch sheets. Arrange 1 flounder fillet on half of each piece of foil; spread each with 1/2 teaspoon ginger and 1/2 teaspoon garlic. Spoon 1 tablespoon soy-sauce mixture over each flounder fillet; top with sliced green onions. Fold other half of foil over fish. To create sealed packets, fold edges of foil over about 1/2 inch all around, overlapping folds. Place packets in baking pan or charcoal grill. Bake packets 8 minutes. To serve, cut an “X” in top of each packet to let steam escape. Peel back foil. Check to be sure fish flakes easily with fork. Garnish with green onion strips and cilantro if desired.