These sandwiches are inspired by cemitas, a specialty of Puebla, Mexico, consisting of a brioche-style bun with a schnitzel filling. We've used bakery-bought slider buns for convenience and added a spicy, smoky chipotle sauce. Most of the elements can be prepared in advance, including the veal schnitzels, which can be fried ahead of time, then heated in the oven when you're ready to serve them. Makes 16.
Note Brioche buns are available from select bakeries and delicatessens.