Hot sauce and little pickled things like onions, cherry peppers, or other hot peppers alongside the sandwich are great! (labreabakery.com)
There were other hot peppers of course, but a hot pepper was a hot pepper, nobody really cared too much whether one pepper was hotter than another. (thechileman.org)
Some cooks use other hot peppers like Arbol or Puya peppers, but canned chipotles are the most used when cooked at home. (mexicoinmykitchen.com)