Zippy ají sauces are mandatory with pollo a la brasa, and they're not just for the chicken: Peruvians also pour them all over the salad and fries that share the plate. This one is mayonnaise-based and bolstered with gutsy seasonings such as garlic, huacatay paste, cilantro, lime, cotija, and jalapeño.
Huacatay is a Peruvian herb sometimes called black mint. You can find it jarred in supermarkets or online. If it's unavailable, increase the cilantro to 5 tablespoons.