FIRST Bring water, stock, and salt to a boil in a medium stock pot. Place rice in a fine mesh strainer and rinse under water for 10 seconds. Add rice to boiling liquid, reduce to low, cover, and cook until rice is tender, about 15 minutes.
NEXT Preheat oven to 400°F. In a small bowl combine sugar, soy, and lime juice and set aside. Divide rice evenly among 4 sheets of paper, mounding in center of each sheet. Top with fish fillet, red onion, chili, and cilantro. Spoon sauce over fish and sprinkle with a pinch of salt and freshly ground black pepper.
LAST Bring two opposite edges of paper together and roll down until paper touches fish. Roll side edges up until a tight packet is formed and no steam can escape. Place packets on a baking sheet and cook for 10 minutes for thinner fillets and 15 minutes if cooking thicker fish such as sea bass or salmon. Place packets on plates and carefully open to serve.