Pinche Taqueria [227 Mott St. (bet. Spring and Prince Sts.); 333 Lafayette St. (at Bleecker St.), Menu]
You want some high quality tacos with high quality ingredients? You've come to the right place. The owner says that they are the "only authentic tacos in New York." I say that I don't care. They taste great and they're relatively cheap. The only problem really is that they're fairly small. But that can always be solved by just ordering more of them!
I usually find that three tacos is enough to shut me up though and I like to diversify my portfolio by going with one each of Al Pastor, Pescado, and a rotation of Carne Asada, Carnitas, and Camaron. The Al Pastor and the Pescado are the standouts that I would recommend the most, which is why I always order them. I also like that all the tacos come with a little bit of guacamole already on them (unlike at some places...Chipotle, I'm looking at you).
Both Pinche locations are small and offer the same menu. Much like Daruma next door (to the Mott Street location), Pinche is a great place for a quick and easy lunch or dinner.