In a small pot, bring all of the ingredients to a boil. Remove from the heat. Cover and let infuse for 15 minutes. Let cool to room temperature, then chill in the refrigerator for 1 hour or until very cold. Strain the marinade through a sieve into a small bowl.
Place a serving platter in the refrigerator for 1 hour.
Meanwhile, in a small pot of salted boiling water, cook the sweet potato for 5 minutes or until tender. Drain and set aside on a plate to cool.
Add the fish to the marinade in the bowl and let marinate for 5 minutes. Drain the fish, reserving the marinade, and place on the chilled serving platter. Top with the sweet potato, mango, corn nuts, shallot, chili, cilantro and fleur de sel. Drizzle with the reserved marinade and olive oil. Season with pepper to taste.
Corn nuts are available in the bulk or snack aisle of the grocery store.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.