The long, ridged doughnut commonly sold at Mexican bakeries is called a churro.
Churros are fried dough pastries usually extruded through a star-shaped nozzle, which creates their characteristic ridges. They may be straight, looped, or twisted, and are commonly coated with sugar or cinnamon sugar. Filled versions can contain ingredients such as chocolate, caramel, or fruit preserves.
Churros are strongly associated with Mexico, Spain, and other Spanish-speaking countries, although their exact origin is debated. Some accounts connect them with Spanish pastry traditions, while others propose influences from fried dough foods encountered through trade and cultural exchange.
A churro is sometimes loosely called a doughnut because both are fried pastries, but it is not normally ring-shaped. The ridged, extruded form is the defining visual feature that distinguishes it from a conventional doughnut.