Preheat the oven to 350 degrees F.
Season each fillet on both sides with 1/4 teaspoon of salt and 1/8 teaspoon of white pepper.
Bring the vegetable stock to a simmer in a large saucepan or deep skillet large enough to hold 2 fillets flat. Add 2 fillets and poach on medium heat until cooked through, about 5 minutes. Remove from the heat and place in a baking dish with 2 tablespoons of the poaching liquid, and cover with foil to keep warm. Cook the remaining fillets.
Meanwhile, spread the coconut on a baking sheet and bake until lightly toasted and golden, about 5 minutes.
Smash avocado in a small bowl with a fork. Add lime juice and season with salt.
To serve, spoon a portion of the rice, and place a grouper fillet on top. Decoratively arrange mango salsa and smashed avocado around fish, and place several tortilla chips in each. Serve immediately.
Yield: 4 servings