Whisk lime juice, chili powder, cayenne, and salt together.
Toss the lime juice mixture with the cashews until they’re well coated.
Spread the cashews into a single layer onto a baking sheet lined with parchment paper or a Silpat, making sure to scrape out as much of the lime juice mixture as possible. Bake for 60-90 minutes, stirring every 15 minutes so that they cook evenly.