Peel the mango, cut into slices, and drop into the feed tube of a running blender to puree. Add the rice wine vinegar, cilantro, garlic, ginger, water, oil, mustard, and lime juice. Season with salt and pepper, to taste, and set aside.
Bring chicken stock to a simmer. In a separate large saucepan on an adjacent burner, heat the olive oil and add the shallots and the rice. Lightly saute: you actually are toasting the rice. Cook until the rice becomes translucent and the shallots become soft, stirring constantly. Add the white wine to deglaze the pan. Begin slowly adding the warm stock, 1 ladle-full at a time, to the rice pan, stirring as you go. This will bring out the starch in the rice and make the mixture creamy. As the mixture absorbs the broth, ladle more into the pot.
When the first ladle of stock has been absorbed into the rice. When all of the stock has been ladled into the rice pot, slowly simmer until the rice is soft and creamy. Stir the butter into the risotto for more flavor and creaminess. Set aside, keeping warm until needed.
Heat a saute pan for the fish. Rub fish fillets with oil, salt and pepper. Place in pan, skin side facing up. Turn the fish over after 3 to 4 minutes. Cook for another 3 to 4 minutes or until done. Do not overcook the fish. It is done when the flesh springs back. Remove the fish to a utility platter. Place a mound of risotto on each plate. Top with mahi-mahi. Drizzle some mango sauce around the plate and top with chopped scallions.