Translated: Small, corn tortillas with beef or pork or tongue or brains with a little onions and cilantro. Nothing more.
Real Mexican tacos don't come with lettuce, tomatoes or cheese. Adding those makes it the American version.
That is certainly not true. The best tacos I ever tasted -- and second place isn't even close -- were sold by a woman who had a little carry out in the triangular space under a stairway off a plaza in downtown Guadalajara. The corn tostadas were handmade and kept in a large blue plastic drum. She put a teaspoon of some of ground meat paste of some kind on the tortilla, heaped a generous amount stingy and very, very thinly sliced lettuce over that, added some shredded queso fresco, and then poured on a very savory thin tomato based sauce. It was unbelievably good and each one cost about five cents. She served Pepsi Cola in sandwich bags which you would drink through a straw by holding the lip of the bag under you index and middle finger.
I've had tomatoes, cheeses and lettuce in tacos from all over Mexico, and in other places not, as you suggest. Another thing I can say is that the food in Mexico City always seemed to be very greasy as compared to other places.
There's a little hole-in-the-wall in Overland Park, KS (105th & Metcalf,) that is said to serve food that is exactly what you'd expect from street taco vendors.
When you pick up your order, all you get is meat on tortillas. The condiment bar has a few different salsas, chopped onions and cilantro, and lime wedges.
Mark
Tacos de Carne Asada is the only way to go. Corn tortillas filled with steak and huge piles of chopped, raw onion and fresh cilantro on the side with fresh lime wedges. Best served with the dark, salsa Rojo from the kitchen. Don’t forget the horchata though.