In this town, it's generally assumed that the further east you travel, the better the Mexican food. Of course, there are any number of exceptions to this rule (see also: El Chato, squarely planted in Mid-City), but it's safe to say that crossing under one of those vibrant blue neighborhood signs that reads East Los Angeles is a good indicator of a tasty lunch.
Right on the Western edge of that section of East LA, that abuts with Boyle Heights, sits Los Cinco Puntos, which you may recall was the winner of our Taco March Madness bracket this year. A squat and vibrantly painted building that overlooks a confluence of five different streets—Cinco Puntos means "the five points"—these guys are at once a neighborhood small grocer, local lunch spot, and takeaway dinner destination.
Like any good Mexican meat market, you can have your choice of cut by the pound, or order up a burrito, quesadilla or taco instead. While there's no place to sit (unless you count the curb, which you should), it is highly recommended that you get in line for a few tacos then and there, instead of waiting to take your meat home with you.