Huancaína (pronounced wan-kay-eena) sauce originated from the Huancayo region of Peru. The story goes that a woman from Huancayo invented the dish, which she served to the railroad workers who were building the high altitude railroad (Ferrocarril Central Andino) from Lima to Huancayo in the Andes. The dish became so popular that it was named after this woman, La Huancaína, whose real name seems to have been lost to history. The key ingredient for this sauce is the spicy aji amarillo chile pepper. These so-called "yellow peppers" look orange or red when ripe, but they turn yellow as they cook, giving this sauce its bright color. Queso fresco cheese is the other main ingredient, a firm but crumbly white cheese that is popular in this region of Peru. The sauce is traditionally thickened with saltine crackers, which add to the distinctive flavor and texture of this unique recipe.