Check with Vicky Zamora, the owner of La Victoria on Haskell near Ross - see http://www.yelp.com/biz/la-victoria-d... for contact information. Vicky is a Tex-Mexpert and knows a woman in East Dallas who makes "the abolsute best pupusas" fresh to your order out of her home.
1605 N Haskell Ave, Dallas, TX 75204
Lilliam Pupuseria Restaurant
2410 West Miller Road
Garland, TX 75041-1301
2121 West Rochelle Road
Irving, TX 75062-7010
I've been to at least a dozen, these have been my favorites. You can't go wrong with any of the ones in Garland. You CAN go wrong with a place that tries to mix salvadoran and mexican. You can go VERY wrong with restaurants run by former Gloria's managers(Mario Sabino's).
Antojitos Salvadorenos Restaurant
2121 W Rochelle Rd, Irving, TX 75062