How to Make It
Using a sharp vegetable peeler, peel half of a mango. Holding the fruit by its unpeeled half, cut 1/2-inch-thick lengthwise slices down to the pit. Then cut crosswise against the pit to release the slices. Repeat the process with the other half of the mango, then repeat with the remaining mangoes. Cut the slices into 1/2-inch dice and transfer to a medium bowl.
In a small saucepan, combine the sugar with the lemon juice and cook over low heat, stirring, until dissolved. Let cool, then pour over the mangoes and toss well. Transfer to a shallow baking dish lined with plastic wrap. Cover with plastic wrap and freeze until semi-frozen, 3 to 4 hours. If the mangoes are frozen solid, let them stand in the refrigerator until slightly thawed. Scoop the mangoes into individual bowls and drizzle with the crème fraîche.