Finally got around to completing my superfecta of Vallejo pupuserias with a few visits to Taqueria Mercy and La Fogata.
La Fogata: this is an easily missable place both in location (a small strip mall on Sonoma Blvd) and in reference (nothing comes up in Google or the local phone book with an address/phone number for this place.)
The decor is sparse but quaint, with a few wooden carvings dotting the walls. A somewhat distracting feature is the money transfer business which is located inside - you'll see customers of both that and the restaurant inside at the same time. There is a counter where you can put an order; however, they do have sit-down service where they'll bring you a menu at a table if you're inclined to dine inside.
The pupusas ($1.50 ea.) are somewhat thicker than the usual and had a nice brown color, but tastewise they weren't anything special and only come in three varieties (loroco, revueltas and chicharron.) The curtido was also decent but nothing more.
Some of the main courses seem more promising. I had the Pollo Ensebollado ($7.95), which essentially seemed to be the Salvadoran version of fajitas - a big platter filled with grilled chicken breasts and carmelized onions, beans, spanish rice and shredded lettuce and tomatoes (interestingly, they had Mexican fajitas on the menu as well for $1 more with the usual choices for meats), with handmade tortillas served on the side. The spice in the spanish rice was barely noticeable, but everything else was good (especially the tortillas) - I was quite stuffed and couldn't quite finish the dish.
The menu has both a decent selection of Mexican and Salvadorean choices, with pretty much everything under $10. The staff all seemed nice and friendly each time I was there.
Pupuseria Mercy: This place defines the term "hole in the wall" - mismatched chairs and tables; a menu board with missing letters and a somewhat confusing arrangement; an aging, stark interior dotted by a few posters and a jukebox; as well as another money transfer business located inside (for a good laugh, check out the sign posting the operating hours for the money-transfer business.)
This is IMHO the best pupusa place in town right now (never got to try the now-defunct Latino's when they were still in business.) These pupusas ($1.50 ea) had a great grilled look to them and their relative thinness (compared to other pupusas in town) helped accentuate the nice, hot cheese and other fillings inside. They also have 9 different pupusas, including zucchini and jalapeño.
Their curtido is also very good - a very crisp and tangy version that edges out Los Gallitos' jalapeño-laced curtido as my fave in town.
I also got to sample their tamales ($2 ea/$20 doz) - I finally got a hint of what a good tamal should be...or at least, the exterior. The tamales were served nicely steamed, and the masa was creamy, dense and delicious. The interior didn't quite cut it, though - chunky bits of somewhat ordinary-tasting pork and chicken with interlaced with the occasional potato hunk.
The bilingual english-speaking lady (who I assume is the owner) is very friendly and helpful.
They do have some of the typical Mexican items like burritos and the like, but for me, the pupusas and tamales are what's worthwhile here.
My informal ranking of Vallejo pupuserias as of now:
1) Pupuseria Mercy
2) Los Gallitos
3) El Emperador
4) La Fogata
La Fogata Salvadoran & Mexican Cuisine
2428 Sonoma Blvd
Pupuseria Y Taqueria Mercy
333 Tennessee St