I spent just a night last year in Mexicali. There is not much to see beside a pretty good museum.
The town is far less touristic than Tijuana and feels much less secure too, especially at night...
In fact the city center was as I was expecting Tijuana to be: dusty, poor, sad and grim and it seems to me I was the only gringo around.
Anyway the specialty doesn't seem to be food here but medical cares that probably cost much less that in the States.
During a quite long walk to the museum, I've been amazed by the number of clinics offering all specialties, I've came across dozens of them!
http://www.stereoscopie.fr/php/showonmap.php?coords=-115.478804,32.664181,1&cmt=Clinics
Pierre Meindre.
(260K)