I have eaten some of the best tacos...
at a taqueria called el Zorro just across the corner from City Lights Books. Super fresh chorizo, good tortillas, excellent variations on the usual salsas (there is one that is smoky and vinegary almost like NC BBQ...so good) and as many grilled serranos or habaneros as your little gringo stomach can take! Aside from that, a not too sweet horchata. Four huge tacos, two horchatas and about 15 serranos for less than $15 bucks! And the Argentine Classico on TV. I couldn't have been closer to heaven if I was sitting in the lord's lap!
Here's an extensive exploration from a couple of years back:
If you're at a loss, the taqueria at Otaez (not the restaurant, but the
taqueria attached to the restaurant) is a good bet. On International
at the corner of, I'm pretty sure, 39th.