- Dried chiles de árbol or 1/2 teaspoon crushed red pepper flakes
- 4 ounces torn stale crusty country-style bread
- Preheat oven to 200°.
- Heat a dry medium ovenproof skillet over medium-high. Toast 2 dried chiles de árbol or 1/2 teaspoon crushed red pepper flakes and 4 ounces torn stale crusty country-style bread, stirring occasionally, until bread is charred in spots, 6–8 minutes.
- Transfer pan to oven and bake until bread is dry and crisp, 1–1 1/2 hours.
- Working in batches, grind chiles and bread in a spice mill to a fine powder.