LIMESTONE, Tenn. (WJHL) — If there was a most popular pastry contest, the doughnut would have to be in the running for the top prize.

But fans of the fried rings of sugar and carbs will tell you, not every doughnut is created equal.

“We believe that the best doughnuts are made in a certain way and with the best ingredients,” said Ruth Kauffman, co-owner of Auntie Ruth’s Doughnuts.

Kauffman would know. Her Tri-Cities based food truck business attracts long lines every time they appear at festivals, farmer’s markets, and business parking lots.

“We are just really humbled by it,” Kauffman said. “Everybody has been so good.”

The booming business began as a hobby for Ruth and her husband Roman Kauffman. With no expectations of making much money, they set up a simple doughnut operation at the Unicoi County Apple Festival in 2006.

“We had a little tent set up with a little mixer and a little fryer,” said Kauffman.

The response, she says, was stunning.

“It was crazy. We were blown away.”

Just like that, the Kauffman’s had a new family business, and it needed a name.

“A lot of people ask who Auntie Ruth is,” Ruth said. “They think she’s long dead and gone. But yes, it’s me.”

The next year, the Kauffman’s set up at the Johnson City Farmer’s Market. Fans found them. Long lines formed, so the Kauffman’s scrambled and bought a food truck.

Soon, they bought another one.

“Currently, we’re at three food trucks,” Ruth said. “We could have six or eight if we wanted to.”

That would at least start to meet the barrage of requests from business owners who’ve figured out that, in order to get a crowd, all you have to do is park an Auntie Ruth’s doughnut trailer outside your front door.

But the Kauffmans aren’t in a hurry — the couple seems determined to avoid growing pains. “To us, quality matters more than quantity,” Ruth said.

And it’s clearly about something bigger than doughnuts. And pretzels. (Did we mention their pretzels are another signature treat?)

“We want to sell a good product at a good affordable price and treat them as a person that is worthy to be respected,” said Roman Kauffman.

“It would make it a lot easier if we would go with powdered milk and powdered eggs,” Roman said. “It would make everything easier. But we’re not convinced the product would be the same.”

When a business is successful, it’s no surprise others will seek to replicate or emulate.

As for the Auntie Ruth dough recipe, “It is a protected recipe – yes,” Roman said. The Kauffman’s say they’ve sold access to the formula and even sold food trucks for donut businesses.

“It’s sort of my retirement plan,” he said.

But with this hard-working couple, there are no attempts at pretense. “It’s just a doughnut,” Roman said. “If you want a doughnut business, just find any good recipe and get to work. People will buy a fresh hot doughnut.”

But one thing isn’t a secret about Auntie Ruth’s success. The Kauffmans are open about their Mennonite faith.

“I think when you are serving the Lord, you want to do your best,” Ruth said.

Their newest venture can be found along Highway 11-E in Limestone. The first “brick and permanent” Auntie Ruth’s doughnut shop permanent location just opened for business. The Kauffman’s say it will allow them to sell donuts all year long (apparently it’s hard to make donuts in a food truck when it’s cold outside).

And Roman is quick to add that won’t be their last.

“We’re thrilled to have a brick and mortar shop,” he said. “It’s changed the way we’re able to do business.”

The food truck side of the business will continue to grow as well, he says. Fans stalk their weekly Facebook and Instagram updates to find the hand-crafted baked treats.

Auntie Ruth herself says it’s all a dream come true.

“It really is. It really is,” she said. “It’s amazing. The local community has blown us away.”