Memelas are antojitos (appetiizers or snacks) from Oaxaca, similar to tlayudas/clayudas (Oaxacan “Mexican pizza”). Oaxacan memelas are a local name for the identical sopes that are served in other parts of Mexico. 
 
Memelas are corn masa cakes topped with beans, salsa, shredded cabbage, guacamole and cheese. Memelas have been served at Oaxacan/Mexican restaurants in the United States since the 1990s.
 
 
Oaxacan Foods
Memelas - are best described as toasted Oaxacan pizzas - very healthy, the corn masa is flattened with a tortilla press then placed over a hot comal or griddle. Topped with Black Beans, Our own Mole Negro, Queso Fresco, Cabbage, Guacamole, and Salsa.
   
Gourmet Sleuth
Memelas
Similar to sopes or huaraches, memelas are grilled thin masa cakes topped with beans, salsa, cabbage, guacamole and cheese.  The toppings vary from recipe to recipe and it’s a good recipe to improvise using your favorites.
 
Planeta: What to Eat in Oaxaca
Oaxaca is a paradise for those who love corn. The multitude of options, names and serving times can be confusing.
 
Try the memelas, tortillas topped with lard, crumbled cheese and salsa. Modern incarnations include beans and the option of a layer of tinga (shredded chicken with tomatos, onions and chiles) or potatoes and sausage.
 
27 October 1991, New York (NY) Times, Pg. XX22 ad:
“Memelas” are sandwiches served with cream, mustard, chile and sardines.
   
Google Books
A Cook’s Tour of Mexico:
Authentic Recipes from the Country’s Best Open-Air Markets, City Fondas, and Home Kitchens
by Nancy Zaslavsky
New York, NY: St. Martin’s Press
1995
Pg. 157:
Memelas are handmade, thick, oval tortillas stuffed with black bean puree.
     
Google Books
Spanish for Dummies
by Susana Wald
Hoboken, NJ: John Wiley & Sons
1999
Pg. 83:
Memelas (meh-meh-lahs) in Mexico are tortillas that are pinched on the side to form a hollow, which is filled with pastes and delicacies. 
 
Epicurious
Memelas with Queso Fresco and Charred Tomato Sauce
Gourmet |  May 2001
 
Memelas are similar to chalupas and sopes. Pinching up the edges and creating tiny bumps in the centers helps keep the filling in place, which becomes important when the memelas are large.
Active time: 1 3/4 hr Start to finish: 1 3/4 hr
Servings: Makes 16 hors d’oeuvres.
 
Ingredients
1 lb tomatoes (4 medium)
2 fresh serrano chiles or 1 jalapeño chile
2 tablespoons chopped white onion
1 teaspoon salt, or to taste
1 tablespoon vegetable oil
1/4 cup chopped fresh cilantro
2 cups masa harina (“masa mix”) such as Maseca or Quaker
1 1/3 cups warm water
10 oz queso fresco (Mexican fresh cheese) or feta, crumbled (2 cups)
Garnish: chopped fresh cilantro (...)
 
24 January 2002, Los Angeles (CA) Times, pg.
Memelas are thick tortillas topped, like clayudas, with asiento, beans and cheese. 
 
Google Groups: sdnet.eats
Newsgroups: sdnet.eats
From: .(JavaScript must be enabled to view this email address) (Bos34)
Date: 12 Aug 2002 18:14:09 GMT
Local: Mon, Aug 12 2002 1:14 pm
Subject: Re: El Salvador Pupuseria y Restaurante
 
Loroco adds a malt-like flavor to the pupusa, and can be very enjoyable. For those who are unfamiliar with pupusas, they somewhat resemble Mexican gorditas or memelas; imagine an extra-thick tortilla with a layer of stuffing in the middle.
     
AccessAtlanta
Mexican? No, Oaxacan
By MERIDITH FORD
The Atlanta Journal-Constitution
Published on: 06/22/04
(...)
The same goes for sopes, called memelas in Oaxaca (and at Fandango) — thick, handmade tortillas full of corn flavor spread with bean sauce, cheese and shredded cabbage. 
 
LA (CA) Weekly
Oaxacan Snack Attack
By Jonathan Gold
Thursday, September 16, 2004 - 12:00 am
(...)
At the base of the botana plate, forming something like the solid foundation supporting a three-story house, are a half-dozen memelas, thick corn cakes with the heft of movie theater–size chocolate bars, indented and charred where the dough hits the hot metal of the grill, chewy as a medium-well steak. Other restaurants in town feature memelas, often fried, smeared with beans and drizzled with melted pork fat, but the memelas at Antequera de Oaxaca are creatures unto themselves, crisp on the outside and steamy within, perfect for transporting guacamole, a bit of meat and the restaurant’s superhot table salsa.
     
Immaeatchu
12.21.2005
Antequera de Oaxaca to the Rescue
Also included in this beautiful styrofoam box is a chile relleno (so fricking spicy. only ate a small bite.), thick memelas (corn cakes) grilled with pork fat, and chorizo.