1Up to a few hours ahead or during preheating, mix together the juice from one lime, brown sugar, soy sauce, and rice vinegar. Preheat oven to 425*F. Remove skin from fish (optional) and place in a large ziploc. Pour in marinade, wiggle it around a bit to fully coat the fish, then let it hang out in the fridge until you're ready to cook. Chop mint (about 1 tbsp) and set aside.
1Place silpat on top of baking dish and arrange fish on silpat equally spaced. Pour remaining marinade in your saucepan. Heat on medium and reduce by about 2/3 until it's thick and syrupy. Spoon onto the top of the fish or use a pastry brush if you have one. Cook fish for about 12 minutes until it just begins to firm up. Remove from oven.
2 Turn on your broiler. Once it has preheated place fish in center of oven and broil for about 1 minute until the top gets just ever so slightly charred. Remove from broiler and serve with fresh chopped mint.