The nopales and the salsa were my doing, but at this corner taquería, papas a la Francesa are de rigueur. During my two-week visit to Mexico City, I don't recall seeing fries on tacos anywhere else; perhaps this overloaded presentation is more the fashion in the state of Michoacán. (Uruapan is its second-largest city.)
Fellow customers, four motorcycle policemen among them, picked off most of their fries before taking tortillas in hand, but given the example of my own taco (16 pesos, about 80 cents at the time), this needn't be dogma. ¡Bistec y papas unidos!
Taquería Uruapan
Corner of Uruapan with Av. Insurgentes Sur, Roma Norte, Mexico City
(From a March 2017 visit)