Preheat oven to 140 degrees (or as low as your oven will go). Prepare a lined baking sheet by lining with parchment paper or a silcone baking mat.
In a food processor or blender, puree fruit with sweetener and lemon juice until perfectly smooth.
Pour pureed fruit evenly over baking sheet.
Place in oven and bake for 4-6 hours, until set and no longer sticky to the touch. ***See note
Allow to cool, then remove from baking mat or parchment paper.
Cut into 1 inch strips and roll up in parchment paper or wax paper and secure with tape or a sticker to make it cute.
Be sure to spread your fruit mixture thin, but without any holes--so an even layer about 1/8-1/4 inch thick.
I used 2 cups Strawberries and 1 cup Blackberries for this recipe.
You can use frozen fruit. Just defrost first in a strainer over a bowl in the refrigerator to remove excess water. Drain well and pat dry before proceeding with the recipe.
It can take up to 8 hours to cook these fruit roll-ups if your fruit has high moisture content and your oven is set at 150 degrees. I have only ever had to bake my fruit roll-ups for 5 hours. But you may need longer. Check every 30 minutes and remove from oven when no longer sticky to the touch.