On the recent Chicago – Milwaukee Roadfood Tour, I had the pleasure of dining three days in a row at Xoco, Rick Bayless’s newest place.  It is immediately adjacent to his 2 other restaurants and features a casual eatery open for breakfast and lunch Tu-Sa.  The breakfast menu is served 8-10am, pastries only till 11am and then the full soup, sandwich (tortas) and specials menu through mid-evening. (I think it was 8pm) 
Lines can occur although my early dinner of 4:30pm yielded no line and a chance encounter and picture with Rick.  The next two days, we arrived at 7:30am for an 8am opening and were first in line each morning.
If 3 days in a row, in the middle of a food tour doesn’t tip my hand…I’ll say it…FANTASTIC!  Expect to pay $10-12 per person, and you’ll want to go back the very next day.
You can see the menu except for specails by googling Xoco in Chicago.