Caribbean Lime Mousse

Using a microplane zester, remove zest from limes and set aside. Squeeze and strain juice from limes into a small bowl and set aside. Heat the water in a saucepan until steaming (do not boil). Whisk in the flour, cornstarch, salt, and 2 cups sugar. Cook, stirring constantly, until lightly thickened. Separate egg white from egg yolks and set each aside. Whisk together the egg yolks with the lime zest and vanilla. Using a small ladle, add a small amount of heated mixture to egg yolks, stirring briskly to temper. Do this a couple more times, then gradually stir the egg yolk mixture into the saucepan, whisking briskly as you do so. Quickly stir in the lime juice, butter, and heavy cream. Cook, stirring, for 2-4 minutes or until thickened; remove from heat. In a large mixing bowl, beat egg whites until very stiff. Fold beaten egg whites into lime mixture, stirring gently until blended. Spoon mousse into 4 large wine glasses or dessert dishes. Sprinkle each dessert with about 1 tbsp shredded coconut. Cut each lime slice almost in half, stopping cutting just at the edge of the peel on one side. Dip lime slices into granulated sugar, if desired, and shake off excess. Twist cut sides of lime into two opposite directions and lay on top of mousse. Chill for 2-3 hours or until firm and set, before serving.