"I said, 'What is a cheese curd?' "
Windham, who grew up in Illinois a mile from the Wisconsin state line, stared at her husband, who grew up in the coal country of Shenandoah, Pa.
"Just the best thing you'll ever eat."
Mitchell agreed when they visited the fair circuit in the Upper Midwest, where fried curds are as ubiquitous as shoofly pie and funnel cake are here.
The curds are young pieces of cheese, usually Cheddar, cut into pieces before processing; they're battered and fried. Not rigid like mozzarella sticks, a cheese curd weeps gently through the crust outside a creamy center.
Mitchell began selling curds at festivals. He said he would explain what they are, and "it becomes much easier to sell after their first bite," he said.
Emboldened, he told his wife "we have to run with the cheese curd."
He left teaching and decided to start a food truck to sell the snack on a smaller scale as a sideline to his concession business.
Mitchell wanted to improve the taste. He visited dairy farms in Wisconsin and found a farmer who would provide the kind of curds he wanted - "made Tuesday, shipped Thursday, eaten on Saturday."
Mitchell hired a chef, Mark Tropea, who refined the process, adding beer to the milk and tweaking the batter.
Last month, Mitchell took his new white truck - dubbed the Cow and the Curd - on its maiden run. He pulled up to a beer shop's parking lot in Fishtown and opened the side window. Soon, the aroma of frying curds filled the air.
Onlookers gathered by the truck, whose logo is a cow licking its lips topped by the words "Battered Fried Cheese Curds." Signs explain what a cheese curd is.
"But nobody reads signs," Mitchell said, the English teacher in him coming out.
It usually takes a Midwesterner to go first. Then everyone gets it. The first customers that night seemed happy with the snack. "It espouses the beer and wine scene like nothing else," Mitchell said.
For now, Mitchell is parking the truck at night near the bars in Fishtown, though he is being booked at wineries and at beer festivals.
"I never tasted anything like it," said Claudia Post, a small-business consultant who sampled curds at the Bottle Shop East for the first time. "It was like eating velvet wrapped in a crunch."
To find the truck, try Facebook or Twitter.
Contact Michael Klein at firstname.lastname@example.org.