for banh mi, i like ba le, but then again, i don't have what i am sure are super SF banh mi offerings to compare the ba le banh mi to. i'd be curious to know what made the SF banh mi so excellent.
vin phat bbq has, iirc, only one type of banh mi, but i know others really like it (i had it once, and i thought it was ok). tank's banh mi also gets high marks, too.
for burritos with black beans, i second the burrito buggy recommendation. the loop has, for all intents and purposes, an incredible lack of decent food, both high- and low-end. but burrito buggy, from my many experiences, offers a fantastic burrito with black beans.
Ba Le French Bakery & Restaurant
5018 N. Broadway
Chicago
Vinh Phat BBQ
4940 North Sheridan Road
Chicago, IL 60640
Burrito Buggy on Van Buren
206-208 W. Van Buren St.
Chicago
Burrito Buggy On Clark
201 N. Clark St.
Chicago