Chef Scott Simpson was flying down I-5 in his "bitchin' 66 Econoline truck rod," the wind in his "'70s 'do" -- as he referred to his long brown ponytail. It was the summer of 2004. He'd just sold his comfort-food kitchen, Blue Onion Bistro on Roosevelt, and hadn't yet opened Fork, his funky-yet-formal Capitol Hill dinner house. He was happy, he said then, because he was "retired" (albeit temporarily) and because there was so much more he wanted to do with his life.

Mr. Simpson, born Aug. 4, 1972 in New Jersey, died early this week in Seattle. He was 38.

Simpson was the chef and owner of Lunchbox Laboratory, a Ballard burger shack known for its erratic hours, its "dork" burgers (a mix of duck and pork), and customers willing to wait outside in the rain to get their hands around his mile-high specialties. In December, Mr. Simpson closed his Ballard spot, relocating to South Lake Union where Lunchbox Laboratory stands today as a 5,000-square-foot full-service restaurant: a testament to his love for collectible kitsch, his favorite comfort foods, and the success of his creative genius.

Scott Simpson, at the original Lunchbox Laboratory in Ballard, in 2008 [Seattle Times/Rod Mar]

"Scott was extremely inventive and creative," said Arnold Shain, Mr. Simpson's business partner, along with John Schmidt, at the new Lunchbox Laboratory. "He had a great sense of how to stretch his potential customers' mind, to give them what they didn't think about getting -- until he showed them a new horizon.

"In my 48 years in the restaurant business, I've seen a lot of talent," said Shain, a restaurant consultant. "And what he did better than anybody else was that he was a magnet. He was a Pied Piper. Customers would come no matter where he was, and from a business standpoint that was magic."

Shain recalls getting to know Mr. Simpson at the Blue Onion Bistro, where the decor was a junker's delight, the menu made him a critic's darling and the chef posted notice of daily "specials that change with our mood, which is often." Those who knew and loved him best appreciated his ability to laugh at himself -- and the frankness with which he publicly discussed his bipolar disorder, diagnosed in his 30s. Karen Long, who managed the dining room at Blue Onion Bistro and the short-lived Fork, remembers how he'd feed the homeless men who'd walk by, often inviting them into his office to watch football.

Mr. Simpson was raised in Scottsdale, Ariz., and there attended Le Cordon Bleu College of Culinary Arts. Even as a youngster, he was a "dear gentle soul, a friendly sensitive kid with an incredibly wacky sense of humor," recalls his childhood friend Jason Baehr of Long Beach, Calif. Mr. Simpson suffered a lot in his young life, said Baehr, losing his beloved older brother Chris to cancer while Mr. Simpson was in junior high, closely followed by the illness and death of his father, Chuck.

"I talked to him on Sunday night," said Baehr, "and it was an emotional conversation." They reminisced, and Mr. Simpson told his friend he expected to live till he was 60. Baehr responded by saying "You have so much potential," noting that now, with corporate business partners to help run Lunchbox Lab he'd have the time to focus on his own well-being. Instead, in the days to come, Mr. Simpson took his own life.

"When I met Scott four years ago, he was so happy and alive in his own skin, so ready to run out and grab life," recalls his girlfriend Allegra Waggener. At the time, he had recently dropped 200 pounds through a gastric bypass, after a lifetime spent struggling with his weight.

His loss was Seattle's gain: Together, he and Waggener opened Mr. Simpson's culinary magnum opus, Lunchbox Laboratory. If he were to hoist one last burger, Waggener said, it would be his "Burger of the Gods," built with blue cheese and caramelized onions. And he'd eat it with no regrets.

Mr. Simpson was predeceased by his parents and his brother. A memorial service is pending.