A deli chain you've probably never heard of is gearing up to be the next Chick-fil-A

A small deli chain was just named one of the most profitable restaurant chains in the US.

Jason's Deli was No. 2 on QSR Magazine's ranking of the average sales per unit of the 50 biggest brands in the quick-service industry. The deli chain only trailed behind industry champion Chick-fil-A. 

While the chain has just 260 locations, a single restaurant made an average of $2,664,000 in sales in 2015. That's six time as much as deli rival Subway, with average unit sales of just $424,300.

Average unit sales are a key measure of success in the restaurant business.

Long-time leader of the list, Chick-fil-A, proves just how important the figure is for measuring growth - the chain's high average sales per restaurant allowed it to become the No. 1 chicken chain in the US by sales, despite having less than half of the number of restaurants as rival KFC.

The first Jason's Deli was opened in 1976, in Beaumont, Texas.

The chain is known for its deli classics: soups, sandwiches, and salads. Since 1980, chain's signature sandwich has been the Muffaletta, a New Orleans favorite made on crusty, grilled bread.

Jason's Deli has a more extensive menu than most fast-food or fast-casual chains, however, with pasta, baked potatoes, chicken nuggets, and even a full salad bar.

Also notable: the chain serves up free soft serve ice cream to all customers.

Despite its basic deli feel, the chain has doubled down on nutrition in recent years.

In 2005, the chain debuted its vegetarian menu and stopped using partially hydrogenated oils. Since then, the chain has cut MSG, high-fructose corn syrup, and artificial colors and dyes from the menu. The chain has also launched gluten-sensitive and vegan menus.

As the chain updates its menu, it has also begun to update its technology. In 2015, the company launched drive-thru concept Jason's Express, and in April, announced it had begun a test of delivery with DoorDash.

Part of the reason why Jason's Deli's average unit sales are so impressive is because menu prices are simply higher than competitors like Chick-fil-A and McDonald's. However, as sandwich standbys such as Subway struggle, the ongoing success of Jason's Deli could signal that the chain has the potential to win over Americans in search of a new deli.