Pup 'n' Taco thrived until it didn't, serving burgers, tacos, hot dogs and pastrami for almost 20 years starting in 1965 until Taco Bell bought all the buildings: 99 in total.
This image was posted on Reddit and there was some confusion about the menu. Someone (who clearly has never been to L.A.) found the menu discordant. But this is exactly how it's done in the spiritual home of American fast food.
Allow me to quote myself in an article for Serious Eats:
On the best coast, pastrami transcended that narrow category years ago, mostly at the many, many, anonymous-in-their-ubiquity burger stands around Los Angeles County, which are largely on the eastside, adorned with signs touting their "BURGERS TACOS PASTRAMI." Pastrami sandwiches at these spots are a comfort food mix that really represents what Southern California is all about: hot pastrami adorned with the likes of shredded iceberg and pickled jalapenos...
"I don't personally eat pastrami Hat-style," says Wexler. "I'm a purist. But it is uniquely Los Angeles-style, and when researching [for my deli], this certain type of place kept popping up, the little stand with tacos, burgers, pastrami, sometimes yakitori. And always named something like Tom's or Jack's. It's part of the LA food journey, very representative of who we are as a city." Indeed, Angelenos don't bother much with tradition. The delis here serve bacon, and you won't be shunned for getting your sandwich on sourdough or adding Anaheim chilies or jalapenos or banana peppers.
There isn't one specific moment or recipe to point to that explains how pastrami became a quick-service headliner in LA, right alongside burgers and tacos. It can be tracked pretty closely to LA County's migration patterns, though. Boyle Heights, a neighborhood just east of the LA River, was the center of the Los Angeles Jewish community (along with other pockets like Montebello, downtown and Westlake) up until about the 1920s. At that point Jews began migrating to the westside, while Central Americans (especially Mexicans escaping their war-torn country) became the dominant cultural force in the old neighborhoods. But the eastside held on to that pastrami.
There is a trove of Pup 'n' Taco commercials on YouTube: it looks like the chain mastered the lost art of the 10-second commercial.
There is also this moment from the movie "Fletch" that I suppose was hilarious to a lot of people in 1985 (and it was, people mention it online a lot), but seems so stupid right now - like, not even racist, really, just pointless.
But to end on a fun note, one more 10-second banger.