Shoot, there are whole books on just chiles rellenos. Or enchiladas. Or tamales.
So I always start out by trying to pin down exactly what the person means by "real".
As a starting point, here is a response that I recently gave to someone on Houston Foodie Friends on Facebook.
Following that, are screenshots of a typical Mexico City restaurant. To give you some help in figuring out what type of cuisine you might be interested in locating in Houston.
Jay : " Most of the non "Tex-Mex" places here in Houston focus heavily on meats and the northern Mexico style cuisine. A good starting point for this type of food is/are: Taqueria Alma Latina, Taqueria Arandas, Taqueria Laredo's, Tostadas Regios, etc. And the steam tables at Fiesta and Mi Tienda grocery stores.
Gerardo's Meat Market on Patton is where a lot of people go for barbacoa.
I have a soft spot for Trigo's Mexican Restaurant on Irvington because their flour tortillas are very good.
For lamb shoulder and cabrito, you must check out El Hidalguense on Long Point.
For more southern and central Mexico style, you have the Caracol/Xochi/Hugo's restaurants to choose from. And Cuchara on Fairview and Pico's on Richmond. And mole Poblano at Guadalajara Bakery on Dunlavy or Houston Bakery and Cafe on Fulton.
For breads, check out El Bolillo. And while there, be sure to visit Canino's across the street, Reyes Produce one block away, and the Mercado y Carnicería Reyes. More info on the Farmer's Market is here on my blog. Special note: my absolute FAVORITE chorizo in Houston is the house made, family recipe, chorizo at Reyes Market.
For northern style barbacoa, you could go to Gerardo's on Patton. A Houston institution.
For Tampico style fish, you have Tampico Seafood on Airline (and also on Hwy 45) and for tortas de la barda (Tampico style with pork, ham and all the fixings) you have Puerto Jaibo and Taquería Las Balas locations.
For steam table choose your own meats option you have Buey y Vaca on Airline and at several other locations. And the Mi Tienda grocery stores and the Fiesta grocery stores.
For typical antojitos you are probably gonna want to go to one of the two Gorditas Aguascalientes locations. One of my favorite places to take visitors from out of town.
For Mexican style sandwiches with telera bread, aka "tortas", go to Mexico's Deli on Dairy Ashford.
For a comida corrida, such as you might find in a multitude of comedores in Monterrey, I highly recommend Los Morales on 75th Street. Another choice for Monterrey style cuisine would be the La Silla restaurants around town, or, the Tostadas Regios locations around town.
For Mexico City style tamales you will want to go to one of the Tamales Doña Tere locations. And I know for a fact that their mole Poblano is made from scratch, and is not from a jar. For the smaller, northern style tamales, a good choice is Alamo Tamales on Berry.
For the heavy, meat oriented plates so popular in northern Mexico, one has the choice of Vaca y Buey, or, one of the two Teotihuacan restaurants that have built their reputation around a parillada of assorted grilled meats as you can see in this photo:
For Jalisco/Michoacan style birría, try Trudi's on Hillcroft.
For Puebla style cuisine, try Fonda Santa Rosa on Beechnut.
For Huastecan/San Luis Potosí style cuisine, try Huasteca Mexican Grill on Wilcrest or El Campesino on Bellaire Blvd.
I am going to post a screen shot of a typical menu in Mexico City for you to look at to see which type of dish you want to try and then I can probably recommend a place to you."
A typical lunch time meal is the comida corrida, a fixed price (at today's currency exchange, about $4) meal that includes beverage, pasta, soup, entree, dessert and bread or tortillas.
Here are some typical lunch offerings in Mexico. Click on each image to enlarge it as needed: