The guy outside Supermercado Guanajuato on California just south of Belmont has the best tamales to go I've found. $7.00 a dozen, nice light texture. Not just pulled out of a cooler, he's got a real tamale wagon with a burner and two steamers on top, one for red, one for green.
Also noticed further down on the board people wondering about the food trailers in Humboldt Park. The best one I know of (and all the Puerto Ricans I work with agree) is on Munoz Marin Drive, which is the road that runs north through the park from Division east of Kedzie.
Don't see much about Puerto Rican food on the board, actually. Lots of it is too salty, and it's a meat thing to boot, but if you like it, check out Las Palmas on Homan somewhere around Augusta (w. side of the street). It's just a little storefront, you pick up a tray to serve yourself from the fried food under hot lights in a case by the front window, and/or point and choose from about a dozen different choices in a steam table. Stewed meats, baccala, couple different kinds of rice, different root vegetables, different kinds of beans. Always jammed at lunch (don't know if it's open at night) and always jammed with Puerto Ricans. They don't speak much English, I can't figure out how much things cost, but it's always good and cheap. Try the papas rellenas (a round ball of mashed potatoes stuffed with meat and then deep fried). It's a real cure for the potato jones.
Anybody have any other suggestions for Puerto Rican?