Hidden in the Chelsea Market among artisan food, clothing, and gift vendors, Los Tacos is a great little find. When we visited there was almost no line. I tried a Pollo and Carne Taco, and both were mouth wateringly delicious.
These are big tacos, but you can tell they're made with quality products. Make sure you get the guacamole on top, and I prefer a corn tortilla, but any way you go, these tacos are excellent. They are what you'd expect at a much more expensive sit down Mexican restaurant.
There are also a variety of options on the side to spice up your meal. If you're in Chelsea Market, this is the place to go. My only complaint was, there was almost nowhere to sit, but that seemed to be a problem throughout the market, as people found any place they could to crouch with their food.