Preheat oven to 350 degrees F. Grease 2 baking sheets. Combine the condensed milk, Key lime juice, and flour in a medium bowl. Stir in the grated coconut and then the sugar. If using sweetened coconut, taste the mixture before adding the sugar. Add the sugar only if you think it is necessary. The cookie should have a tangy flavor from the Key lime juice. Drop teaspoons of the mixture onto a baking sheet, leaving 2 inches between each cookie; they will spread while baking. Bake for 25 minutes until they just start to turn golden. Remove from the pan to a rack to cool. Store in an airtight container. * Source: Keys Cuisine - by Linda Gassenheimer * Typos courtesy of: Karen Mintzias