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.