Combine all the ingredients in a blender or food processor, and process until smooth (the ingredients may need to be processed in 2 batches).
Press mango mixture through a fine sieve over a bowl; discard solids. Pour mixture into an 8-inch square baking dish; cover and freeze 4 hours or until firm. Place mixture in a food processor, and process until slushy. Freeze for 3 hours. Soften slightly in the refrigerator for 30 minutes before serving.