Line a baking sheet with parchment paper or a Silpat mat and set aside.
Place mango, lime, sugar, and agave in a medium saucepan.
Bring to a boil and cook for about 7 to 8 minutes, then puree using an immersion blender.*
Continue to cook over medium-high heat for an additional 5 to 10 minutes or until thick and syrupy; the mixture should be thick enough to coat the back of a spoon.
Pour the hot fruit mixture onto the prepared baking sheet and spread evenly into approximately an 8 × 12 inch rectangle.
Place in the oven and bake for 3 1/2 hours.
Turn off the oven and allow to sit overnight.
Cut into strips with a pizza cutter; roll up in a clean piece of parchment paper.
Store in an airtight container for up to 3 weeks.
Notes
*If you do not have an immersion blender, puree in a food processor and then return mixture to saucepan.