pun's post made me proud. I cannot add much to that. I would say that typically the correct sauce for a taco al pastor (loosely a shepherd's taco) would be red salsa taquera, which is usually made from dried chiles de arbol.
There's an informative article
here about tacos al pastor if you would like to try a recipe at home. Remember to keep them small. In grocery stores here they sell a size of tortilla made for tacos that is really small. It is also common to use two of them, or ask for them 'con doble tortilla.'
On those famous tacos arabes from the taqueria Israel..... Yes, only in Mexico would we be celebrating arab tacos from a place named Israel, but, alas, it's true. The owner of this place ran several of these taquerias in Puebla, a town outside Mexico City famous for the talavera ceramics.
Tacos arabes are made of pork and are served on homemade flour tortillas, which is not common. They are pretty large and very generous on the meat. The secret sauce is perfect, and just might combine to make this the best taco in town. Or are the tacos de camaron capeados better? Or a really crispy al pastor, easy on the cilantro, heavy on the piņa and red sauce.....
Another derivative on the al pastor is the gringa. It's basically two flour tortillas (tacos al pastor are traditionally served on corn tortillas) sandwiching al pastor meat with melted cheese. Cut into quarters, add sauce and go! There's another version of the gringa served in town called a sarape, but I don't remember what that is.