Forget about the Summer Olympics. Those with an appetite for nail-biting competition need look no farther than the blocks surrounding 7th Street and Marquette Avenue S. in downtown Minneapolis. Starting most weekdays at about 10 minutes before 9 a.m., a dozen or so brightly painted food trucks engage in a highly choreographed race along the area's grid of traffic-clogged one-way streets. The prize? A parking space.

A 20-foot vehicle affectionately known as "Big Red" is often in the mix. It belongs to Lisa Carlson and Carrie Summer. When these two pedigreed chefs started cooking in a cramped trailer in 2008, there was just one other licensed food truck operating in Minneapolis. Today there are dozens, and surely more are on the way. All of them owe a debt to Carlson and Summer and the pioneering venture they call Chef Shack.

"Before Minneapolis became known -- or even functioned -- as a great street-food city, Chef Shack was dishing doughnuts," said John T. Edge in an interview. He's the author of "The Food Truck Cookbook," a coast-to-coast chronicle of the nation's culinary movement of the moment.

Carlson is a Brooklyn Center native, and Summer grew up in Rochester. Both spent time working for an impressive constellation of starry chefs in New York, San Francisco and London. They've been a couple for 11 years, and naturally, the two 44-year-olds met in a kitchen, when Carlson, who was running an Uptown Minneapolis restaurant, hired Summer. Turns out they work well together, in a finish-each-other's sentence kind of way, and their slightly overlapping skill sets -- Carlson is Chef Shack's chef du cuisine, and Summer handles pastry and manages the business -- are more than complementary.

Chef Shack was born at the Mill City Farmers Market. It started with a suggestion from their boss and one of the market's driving forces, Spoonriver owner Brenda Langton. Tapping into her lifelong obsession with doughnuts, Summer immersed herself in research, bought a mini-doughnut machine from Lil' Orbits in Plymouth and, through a tenacious trial-and-error period, zeroed in on an all-organic formula for what became an instant Chef Shack trademark: diminutive, puffy, melt-in-your-mouth doughnuts, their golden exteriors twinkling with sugar and a nose-tickling blend of cardamom, ginger and nutmeg. Blindly consuming a fist-sized bag is deceptively easy.

Six years, countless 17-hour days and two more vehicles later, Summer estimates that she's made over a million doughnuts. "I never tire of making doughnuts," said Summer. "When I'm 70, I can see myself driving the truck around, making a living making doughnuts."

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Organic mini-doughnuts from the Chef Shack.

The expertise, discipline and ingredient-driven mentality that is part and parcel of the duo's fine-dining background is what set Chef Shack apart from the vast majority of their food truck brethren. After doughnuts, the truck's bestseller is a truly remarkable burger of lean, flavorful, pasture-raised bison. It's an insanely delicious formula: a medium-rare patty brushed with a beef demi-glace and dressed with lettuce, tomato, a runny egg and a slab of Cheddar or pepperjack cheese, all inside a tender toasted brioche bun.

There's more. Braised beef tongue is the foundation for a spectacular taco. Pulled pork, cooked low and slow until the meat teeters towards mouth-melting consistency, is the centerpiece of an awe-inspiring plate of nachos. Vegetarians and vegans also flock to Chef Shack for tacos of pured sweet potatoes, black beans and cilantro, splashed with Carlson's riff on salsa.

The couple are opening a casual, weekend-only bistro this fall in Bay City, Wis. But rest assured, urban Chef Shack lovers, it's business as usual in the city. The distinctive red trucks will keep vying for those premium parking spots, and Carlson and Summer will continue feeding their loyal customers and welcoming new food truckers into the fold.

"I love it when another chef in town gets a truck, and we have to step it up even more," said Carlson. "That's good for everyone."

CHEF SHACK

Saturday: Mill City Farmers Market (8 a.m.-1 p.m.) and Fulton Farmers Market (8:30 a.m.-1 p.m.) Sunday:Kingfield Farmers Market (8:30 a.m.-1 p.m.). Wednesday:Harriet Brewing, 3036 Minnehaha Av. S., Mpls. (after 4 p.m.) Many weekdays on the streets of downtown Minneapolis and St. Paul; track their locations on Twitter, @ChefShack1 and @shackattacks.