The dough gets its name and tang from potato that's deliberately left to ferment ('añejo,' aged) for days before cooking, a step most other Colombian empanadas skip entirely.
Potato is boiled, mashed, and left to ferment slightly before being mixed with egg and fried into small, dense empanadas with a faintly sour flavor. Street carts in Pasto fry them to order and serve them with ají sauce.