The slow transition of Boyle Heights from a Jewish neighborhood to a Mexican / Central American neighborhood means that pastrami is Mexican street food par excellence. You can get a pastrami burrito and it's as heart-stoppingly delicious as it sounds.
Similarly, the 23rd St. Cafe serves great Indian / Mexican fusion.
The small koreatown in STL is still very original. I have to take my Korean cousin, otherwise I don't get service.