From the March 2012 issue of Startups

The epiphany for brothers Chris and Robin Sorensen came one day in 1992, on a sidewalk in their hometown of Jacksonville, Fla.

Fresh off a series of hit-and-miss entrepreneurial ventures--including one called Kris Kringle Christmas Trees that failed to sell a single tree--the brothers had just exited a meeting with executives from a sandwich franchise operation they were considering buying into. They left feeling underwhelmed--and convinced they could do better. What they needed was a concept with which to prove it. Then inspiration struck.

"We went outside after that meeting and came up with the idea for Firehouse Subs on the spot," Robin says. The sandwich chain they once considered buying into soon became a rival. "For a while, we were about one thing: kicking their tail."

Mission accomplished. Eighteen years after opening their first Firehouse Subs restaurant in Jacksonville, the two former firefighters have turned their sidewalk epiphany into a booming national franchise. The theme of the now nearly 500 locations runs from the décor (firefighting equipment, Dalmatian-pattern tabletops) to the food (large toasted subs with names like the Hook & Ladder).

Firehouse Subs ranked third among sub sandwich franchises on Entrepreneur's Franchise 500® list, and company revenue exceeded $285 million in 2011, up nearly 39 percent from 2008. Meanwhile, average unit volume for Firehouse Subs franchises grew from $572,000 in 2009 to $650,000 in 2011.

Firehouse's ability to prosper while the economy tanked owes largely to the tight grip the Sorensen brothers maintain on company strategy and culture. Behind their relaxed, affable demeanor, "we are control freaks," Robin says. The brothers have been especially vigilant about managing growth. They carefully vet store locations and franchisee candidates, while enforcing a one-store-at-a-time approach with franchisees who do come onboard. "We could easily have two or three thousand stores by now," Robin says. "Grow too fast and you can feel the rivets coming out of the wings."

Belying the generous portions Firehouse heaps on its subs is an organization-wide commitment to frugality. While the company has been debt-free since 2001, neither brother took a distribution until 2004, on the 10th anniversary of opening their first store.

A firefighter's courage is also evident in the Sorensens' strategic decision-making. Instead of retrenching when the economy spiraled in 2009, as many of their competitors did, the Firehouse brain trust decided to pump more resources into a radio-focused advertising campaign. "Looking back, putting more into marketing was really risky but a great judgment call," says Shawn Hooks, a longtime Firehouse franchisee in the Southeastern U.S. "Everybody in our franchise area saw significant sales increases because of it. It really paid off."

While they no longer fight fires, a sense of duty to the community clearly still burns in the Sorensen brothers. The nonprofit they founded in 2005, the Firehouse Subs Public Safety Foundation, has raised more than $4 million, most of which it distributes directly to public service organizations. "It's one of the things we're proudest of," Robin Sorensen says. "It has changed lives."

What's more, the brothers believe it gives substance and credibility to the Firehouse brand as it surges into new markets. An international push into Central and South America, and continued expansion domestically, are part of a strategic plan that targets 2,000 restaurants by 2020.

Not bad for two ex-firemen who, without an epiphany, might still be peddling Christmas trees.