Before you begin, make sure to thoroughly wash the oranges, especially if they're store-bought. You'll want to remove any pesticides that may be on the peel. If you can use organic oranges, or homegrown oranges, even better!
Use a vegetable peeler to peel oranges, tangelos, or tangerines into very thin strips. Avoid cutting into the white pith.
If you have a food dehydrator, arrange the orange peels on the trays. Make sure to keep them in a single layer so that the air can circulate around them. Choose the 135°F setting and dehydrate for approximately one hour or until the peels are dry and crispy. The small pieces will start to curl as they dry.
An even easier and faster option is to use the oven. Spread the orange peels on a parchment-lined baking sheet in a single layer. Bake for 30 minutes in a 200°F oven. If after 30 minutes the peels are not crispy, turn the oven off and place the tray back in the oven for 15 minutes or so.
Make sure the peels are completely cooled before blending them into a powder. Store them as is in a spice jar or airtight container for up to a year.
How to Make Dried Orange Powder
Once the orange peels are completely dry, simply add them to a spice grinder or a food processor and pulse until the dried peels turn into a powder. Store dried orange powder in a spice jar and store away from direct sunlight.
Notes
If the orange peels retain any of their moisture, they will eventually mold.
When ready, the dried orange peels should not be pliable. Instead, they should be crispy, brittle, and easily snap when bent.
Another option is to grind the peels into an orange powder that can be used when baking cookies, cakes, and more.
It's important to make sure the orange peels are completely dry before grinding them into a powder. If there is any hint of moisture remaining, it can promote mold growth.
The same process can be used with lemons to make dried lemon peel and dried lemon powder.