Aji Amarillo (Green Peruvian Dipping Sauce)

It was a few years ago when I was introduced to the wonder that is the Pio Pio sauce. A Peruvian restaurant chain in New York City, Pio Pio serves juicy, affordable rotisserie chicken. But it was the vibrant green dipping sauce that I became infatuated with.

I interrogated the waitstaff at almost every Pio Pio location to learn the contents of this spicy sauce. The only consistent answer? That no answer was the same.

Jalapeños and mayo. No, no, aji chiles, cilantro and oil. I had to face the reality that either no one knew what was in the sauce, the ingredients were top-secret, or both.

Light green, medium-hot, creamy, salty, tangy and oh-so-infatuating, it seems that every Peruvian restaurant has its own secret recipe for this mysterious condiment. An internet search for "Peruvian sauce" tells the story of dozens of people anxious to know how to make the sauce for themselves. Helpful bloggers post their recipes on message boards.

One says the secret is a head of lettuce, one swears the sauce cannot be made without evaporated milk, and several point to Peruvian black mint as the key ingredient.

I tried many, many recipes to come close to the magic of Pio Pio's sauce, none of which hit the mark. Finally, I brought a container from the restaurant into work, hoping someone else could reverse-engineer the ingredients. My admiration, along with my frustration, was building, and I needed a slight break from the sauce that taunted me.

Chile Pepper Editor-in-Chief Laura Dankowski took on the challenge, blending my scattered notes from past trials, along with her own hunch of what she tasted. We decided both jalapeños and aji paste (usually found in the Mexican section of grocery stores) were a must, and Laura hit on the addition of cheese, which added the necessary touch of saltiness. It's not exact—but pretty darn close.

At Pio Pio, the dip garnishes rotisserie chicken, crunchy-fried seafood platters and salchipapa, a delicious combination of deep-fried potatoes and sliced hot dogs. But I use the sauce for anything in the place of salsa, whether topping a burger, garnishing a breakfast burrito, or spreading on a piece of fish.

And I'm just glad I can finally stop harassing the Pio Pio employees for the recipe and make it on my own.