Line a baking sheet with parchment paper.

Combine berries, sage leaves and sugar in a food processor or powerful blender and process until smooth.

Pour berry mixture onto prepared baking sheet and spread 1/8-inch thick, as evenly as possible.

Bake for 6-8 hours, until fruit leather is set (center is no longer tacky).

Leaving the parchment intact, use kitchen scissors to cut leather into strips if you want to roll them up or into squares or rectangles if you prefer.