I have seen uncooked mexican longaniza at:
Cermak Produce (at least at the Kedzie location)
4234 N Kedzie Ave, Chicago, IL 60618
(773) 442-8135
La Chaparrita
2500 S Whipple St, Chicago, IL 60623
(773) 247-1402
Cremeria La Ordeña
5958 S. Pulaski, Chicago, IL 60629
773-284-8300
Cremeria La Ordeña #2
3810 W. Lawrence, Chicago, IL 60625
872-208-5581
Part of the secret of a success in life is to eat what you like and let the food fight it out inside.
-Mark Twain