Pour water into a small, microwave-safe dish. Heat in microwave until boiling. Add sugar and stir until dissolved. Add lime juice and rum (optional), then place dish in freezer until cooled, about 15 minutes. With a food processor, puree frozen mango, slowly adding the sugar/water mixture until very smooth. If sorbet tastes too sweet, add more lime juice or mango. Pour into a freezable container and smooth out top with a spatula. (Metal containers aid in freezing faster.) Cover and place in the far back of the freezer for 8 hours. If the sorbet hasn’t frozen to a scoopable consistency, blend in 1/4 cup cold water and freeze for 2 more hours. Repeat if needed. Let sorbet soften on the counter to scoop more easily. Serves 4.
For a nonalcoholic version, stir mixture every hour for 4 hours after covering and placing in the freezer to prevent ice crystals from forming, then continue to freeze for remaining time. If using fresh mango, cut and freeze chunks before starting this recipe.
Per serving: 261 calories, 0.6 grams fat, 0.2 grams saturated fat, 42 grams total carbohydrates, 3 grams fiber, 1.5 grams protein.
