Ají: Spanish for hot Chili-peppers. Ají is a fundamental ingredient and one of the most basic building blocks of most Peruvian recipes; indeed, one could perfectly say that ajíes are ubiquitous in Peruvian cuisine, it's present in most dishes. Ajíes belong to the Capsicum genus of plants from the nightshade family (Solanaceae). Peruvian ajíes are part of the Capsicum baccatum species, which originated either in Bolivia or in Peru and, according to archaeological evidence, was probably domesticated in Peru about 2,500 B.C.

Fresh ajies are always best to use whenever a recipe calls for it, however it is possible to substitute pureed Peruvian aji hot chili peppers for the fresh aji that is called for in the recipes. This is not the case with dried ajies or the powdered aji, those are not good substitutes for fresh aji although they can be useful for creative variations or to introduce a different flavor to some other kind of recipe. Note that when you substitute the pureed aji from the jar for the fresh aji you have to decide on the quantity by taste, just start with a very small amount and keep adding until it tastes the way you like it.

The most well known and used varieties include: Aji Amarillo or yellow hot peppers, Aji Limo or Limo hot peppers, Aji Panca or Aji Colorado or Ancho Chili or Sun dried red hot peppers and Aji Mirasol or sun dried yellow hot peppers.