Aji amarillo is a yellow chili pepper widely grown in Peru. It's the Peruvian holy trinity of cooking together with garlic and onion. It's quite spicy, scoring 30,000 to 50,000 on the Scoville heat unit scale. But despite its heat, it is also known for its fruity notes comparable to passion fruit and mango. And yes, it's yellow, not green, because the cilantro and basil make the sauce green.