It's one of the last hidden worlds of authentic food in Chicago...

A place where few concessions are made to the non-native, and those who want what's good need at least a modicum of the native language and the willingness to look for indications of what might be special...

I've been exploring it for the last few months, all over the city, from Rogers Park to 26th street to the Indiana border. And now I invite you to come with me this Saturday and check out some of these highly authentic places.

What are they? They're the taquerias located inside Mexican grocery stores and supermarkets. One is rightly famous here—
Tierra Caliente, formerly Carniceria Leon, home to
some of the best tacos al pastor in Chicago. But there are dozens, located all over town— hidden in plain sight.

What makes them special and worthy of attention? One, because they're located deep inside Mexican markets, and thus largely unknown to the gringos who live nearby, they have unusually authentic menus with few concessions to non-Mexican tastes (or inability to read Spanish). Two, on weekends they often do it up big with specials such as goat consomme, caldo de siete mares, etc., which you don't normally see on restaurant menus.
I've tried more than a dozen of these places lately, and identified ones that I think are a cut above. Usually I tried tacos de carne asada on the first visit, because that seems to represent 50% of the business at any of these places and was a good way to judge a place that cared from one that didn't; but if they emphasized something else, such as pollo al carbon or tortillas and sopes heche a mano (made by hand)—

—then I used that as the first data point for evaluation instead. So the idea here is, yes, I'll lead you on a tour of the ones that I thought had something special to offer. But one person, even if he's willing to order two lunches' worth of food, can only try so much on a preliminary visit. So I will encourage you to keep a sharp eye out on your own, and together through the power of an LTHForumite hive mind, I hope we can identify other outstanding dishes at the better supermercado-taquerias.
But it will be a
working expedition, with all the possibilities of new discoveries and crushing disappointments that that entails. Oh sure, you can count on some outstanding steak tacos:

and some pastor that might even rival Tierra Caliente:

But I can't guarantee that everything you try will be worth the (guaranteed low) price you will pay for it. On the other hand, only through expeditions such as these can we make discoveries such as a place offering chicken grilled over an authentic hardwood fire (ramshackle enough to make you think you just got off the bus in Guanajuato):

Because these are often small places, I'm limiting the size of the expedition to ten besides myself, of which Cathy2 already has the first spot. Be aware that we're going to do a lot of driving (though a car is not necessary; I assume we'll have room enough if at least 3 drive), and may occasionally dine al trunko in the cold.

The proposed itinerary is still under construction but we will begin at Los Potrillos, 3624 W. Belmont, for goat consomme and a steak taco amuse bouche, at 11:30 am. I will provide everyone with a sheet summarizing my research to date and will be willing to evolve the itinerary as the day progresses; starting in this area, however, allows us to ensure a visit to two of the best up front, whatever else we do.
I look forward to your participation.