Pat them dry with a clean kitchen towel until no moisture remains.
Cut the tops off the jalapenos and slice them into halves. De-seed them as much as you can.
Arrange them in a single layer in your Air Fryer basket.
Air fry the peppers for 20-40 minutes, until they look like this.
Pulse them in a spice grinder for a few seconds until they resemble these flakes.
Notes
Make sure you allow the dried, dehydrated peppers to cool down completely before you grind them. This will give you the perfect texture, and the pepper flakes won't clump together too.
Stop at every 5-10 minute interval and flip the peppers over so that they don't burn.
Wear gloves to protect your hands while slicing the peppers. The heat from the peppers can burn your hands.
I love this flaky, coarse texture, but if you want to, you can also make jalapeno powder by processing the flakes further for a few extra minutes until you get a smooth ground texture.
You can also dehydrate the peppers in an oven if you want to. Simply arrange them on a baking sheet lined with parchment paper and pop them in an oven preheated at the lowest setting and cook them for 4-8 hours until they dry out completely.
If after grinding, you spot any signs of moisture, re-dry the flakes again before you store them.