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 in the same manner.
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 onto a plate, and place a grouper fillet on top. Decoratively arrange mango salsa and smashed avocado around fish, and place several yuca chips in each. Serve immediately garnished with toasted coconut.
Heat the oil in a heavy 4-quart saucepan over medium-high heat. Add the onions, bell peppers, shallots, and garlic, and cook, stirring, for 2 minutes. Add the rice, stir to coat with the oil, and cook for 1 minute. Add the vegetable stock, coconut milk, sweetened cream of coconut, salt, and pepper, and bring to a light boil. Reduce the heat to low, cover, and simmer until the rice is tender and all the liquid is absorbed, about 20 to 22 minutes.
Remove from the heat and let sit 10 minutes. Fluff with a fork, stir in the cilantro, and serve hot with the Poached Grouper.
Combine the mango, poblano, red bell pepper, onions, and garlic in a bowl and stir to combine. Add the vinegar, cilantro, and salt, and stir well. Adjust seasoning, to taste, and serve. The salsa can be made up to 4 hours in advance, and refrigerated, tightly covered.