I work in Calistoga, and since I am not made of money (and only get a 30 minute lunch break, so don't really have time to go out and eat), I generally make my own lunches to bring to work. However, when I don't have one and I'm hungry and I want something quick, hearty, and affordable there is only one place in town I even think about heading to: Vallarta Market.
Unlike almost everything else in Calistoga, Vallarta Market is not on the main street (Lincoln). It is a little pink building on Highway 29 (St. Helena Hwy / Foothill Blvd) just south of the stoplight for Lincoln, with the big sign reading "Calistoga" and an arrow pointing down Lincoln Ave (yes, Calistoga is that small that without this sign you might drive past without realizing it!) If you look carefully, you'll see it right next to the lavender-colored Lavender Hill Spa -- the sign reads "Vallarta Market Carniceria y Taqueria"
It's a small Mexican-style market, with a little grocery/produce section, a "carniceria" (meat/butcher section), and a "taqueria" (taco bar, but also serving traditional plates, quesadillas, and burritos.) I've never actually bought anything from the grocery section, but they do have some enticing Mexican sweets -- candied fruits and vegetables, bags of "fruit punch" fruits, and frozen Michoacan ice cream bars which come in awesome flavors like tamarind, dulce de leche, or even avocado. I'm also pretty sure that when I decide to make some mole, it's quite possible I will just stop here and pick up one of the containers of mole sauce I saw next to the taqueria counter.
Whenever I've been there, I just make a beeline for the taqueria counter -- which is never crowded, but I'm also usually not the only one who stops there for lunch. There's nothing fancy about it, but the food is decent and the prices are pretty reasonable (especially for Calistoga) -- about $6 for a burrito or $1.75 per taco (meat tacos on soft white corn tortillas). I like the fact that I can be adventuresome and try some of the traditional Mexican meats that you might not find elsewhere -- they have some of your standards, like carnitas (shredded pork), pollo (shredded chicken), and asada (beef), but then they also have pastor (one of my favorites -- marinated grilled pork pieces), and pollo asado (roast chicken), and then things get even more interesting with lengua (cow tongue), chicharron (fried pork rinds), buche (pork stomach), and cabeza (beef head).
I'm a pretty adventuresome eater, more or less -- I've tried tripe, fried Chinese chicket feet, frog legs, alligator, rattlesnake, snails, sweetbreads, and Rocky Mountain oysters (calf testicles)... but for some reason it's taking me a while to muster up some courage and try these "leftover bits" of meat like the buche and cabeza. Today I decided to bite the bullet and try a lengua taco, because I had heard great things about it. Indeed, the meat was very tender and moist and tasted a little bit like roast beef (which is what I had heard), but it did weird me out just a little bit that I could see taste buds on the little chopped up pieces. I had heard rave reviews about lengua, so I'm not sure that Vallarta's lengua was up to the hype, but it wasn't bad. I can tell you that their pollo and pastor are pretty good, but I haven't tried the other meats. Not sure I will ever be hungry for buche.
So, if you want an off-the-beaten-path Mexican-style snack, some reasonably-priced meat or produce, or an affordable and authentic taqueria lunch, give this place a try... and don't be shy or scared about the Spanish being spoken all around you; the workers there speak English perfectly fine, and the locals are pretty good and friendly people for the most part.