Piment d’Espelette chiles come from a group of ten villages (one of which is called Espelette) in the Basque region of southwestern France. After harvesting, the chiles are strung together and dried outside houses and shops in the villages—the image of a chile-festooned building is in the logo used to designate this product.
The slightly sweet, mildly spicy chiles are most commonly ground into a coarse powder. In the Basque region, the spice is often used in place of black pepper. It's available online at Chefshop.com.