01 - Set oven or dehydrator to 170 degrees Fahrenheit.
02 - Blend strawberries, mango, and sweetener, if using, in a blender until the mixture is completely smooth.
03 - Line a baking sheet with parchment paper. Pour the blended fruit mixture onto the prepared sheet and use a spatula to spread it evenly into a thin layer approximately 1/8 inch thick.
04 - Bake or dehydrate for 3 to 4 hours, checking periodically, until the surface is dry to the touch yet remains pliable and not brittle.
05 - Remove from the oven and allow to cool completely at room temperature.
06 - Carefully peel the cooled fruit leather from the parchment. Slice into strips using scissors or a sharp knife and roll each strip as desired.