Meyer lemons are often available at specialty markets and have a unique scent and sweet lemon flavor. If you can't find them, use regular lemons.
Peel the mango; remove and discard the pit. Cut the mango into chunks, and place in a food processor, along with 5 tablespoons water, lemon juice, and sugar. Process until the mango is puréed, about 1 minute. Transfer to a small bowl, and serve with Oat-and-Whole-Wheat Waffles.