Start by using a zester or a microplane to collect the zest from each of the fruits. You'll want about 4 tablespoons of zest per jar (this was about 3-4 small fruits).
Using a fork, spread the zest evenly on a baking sheet lined with parchment paper or a silicon baking mat.
Bake on your oven's lowest setting (150-170°) for about 10 minutes. Remove zest from oven when it is dry, but not burnt.
Remove zest from oven and allow to cool. Add zest to jar of granulated sugar and use a fork to gently stir until the zest is mixed throughout.
Notes
Note: Nutrition information is a rough estimate only; actual values will vary based on the exact ingredients used and amount of recipe prepared.