Preheat oven to 400°F. Cut 4 (20-inch) pieces of parchment paper. (I like unbleached parchment for a clean and pure flavor.)
Whisk together miso, zest, juice, ginger, garlic, soy, honey, sriracha, and sesame oil in a small bowl. Pour half miso vinaigrette in another small bowl and set aside.
Season halibut with salt and pepper.
Fold each piece of parchment in half lengthwise. Unfold, and place fillet along each crease. Rub each fillet with several tablespoons of miso vinaigrette.
Fold parchment over fish, making small overlapping folds along edges and sealing with a paper clip. Place on rimmed baking sheets.
Roast at 400°F for 15 to 20 minutes until parchment puffs. Carefully cut packets, avoiding escaping steam, and serve with Asian Slaw.