An expanding fast food chain is cashing in on an untapped market

Wienerschnitzel is the biggest hot dog chain in the world. 

The fast food restaurant has 350 locations. It started 64 years ago as a tiny, family-owned business.

The Irvine, California-based brand has been expanding via a franchise system. The brand recently signed an international franchise deal in Panama - a sign of a possible massive expansion to come.

What's Wienerschnitzel's secret? Tapping into a relatively obscure market.

When founder John Galardi was presented with the opportunity to open his own restaurant, he wanted to serve a different food from everyone else.

"He didn't want to compete with his friend [Glen Bell, of Taco Bell fame] doing Mexican food, a bunch of people were already doing burgers like McDonald's," said his son, J.R. Galardi, chief visionary officer of Wienerschnitzel. "So he decided to go into hot dogs because he didn't see anyone else doing it."

Now, the company serves over 120 million hot dogs a year.

"Hot dogs were just his niche," J.R. said to Business Insider.

Galardi passed away in 2013, but his son, 26-year-old J.R., has taken over the family business.

 The menu at this fast food establishment is relatively simple: it's hot dogs with various toppings.

A new menu item features a hot dog with a special chili sauce, cheddar cheese, mustard, mayo, grilled onions, and bacon.

Core products include the Junkyard Dog, which features fries on top of the hot dog, and The Deluxe Dog, which has a hot dog alongside a pickle. 

You can also order a classic hot dog or a corn dog, too.

The chain also serves chili burger or cheeseburger of a Polish sandwich (Polish sausage on rye bread with swiss cheese and a pickle), or fries.

Wienerschnitzel has a limited breakfast menu, often offers limited-time menu items like fish and chips. 

Toppings on the hot dogs change from time to time, but it's clear the menu is very focused.

For dessert, the restaurant serves ice cream creations.

The brand has stuck to a basic core menu over the years, and calls their main product the "world's most wanted weiner."

 "We've maintained our core product - being chili dogs, corn dogs, fries, milkshakes...and those have remained consistent," he said. "Different products come and go and marketing changes - you know, it evolves over time - but overall, we've pretty much ran the same course with our core products and [that is] what we can attribute our success to: because people know when they go to Wienerschnitzel exactly what they're going for."

But the real secret to keeping the brand thriving, Galardi says, is "understanding your lane. It's realizing what you are and sticking with that." For Wienerschnitzel, that's hot dogs.