A sopapilla is a fried pastry made from a simple dough, usually leavened with baking powder rather than yeast, cut into triangles or squares and deep-fried until puffed and golden, then typically finished with honey, or cinnamon and sugar. It comes from the traditional cooking of the Puebloan and Hispano peoples of the American Southwest and northern Mexico, and later spread nationally as Southwestern and Tex-Mex food gained popularity in the 20th century.
Unlike a yeasted bread, the dough doesn't need to rise before frying, which is part of what gives sopapillas their light, airy interior and crisp exterior. They're most often served as a dessert or snack, but can also be split and stuffed with cheese, beans, or meat for a savory dish.
New Mexico's version, sometimes called sopaipilla, tends to be thicker and puffier; other regional versions add cinnamon or vanilla to the dough.