1. Preheat oven to 425°. Cut parchment paper or heavy-duty foil into six 15x10-in. pieces; fold in half. Arrange lime slices on one side of each piece. Top with fish and asparagus. Spritz with cooking spray. Sprinkle with salt, pepper and parsley. Drizzle with lemon juice.
2. Fold parchment paper over fish; draw edges together and crimp with fingers to form tightly sealed packets. Place in baking pans.
3. Bake until fish flakes easily with a fork, 12-15 minutes. Open packets carefully to allow steam to escape.