On a whim, Dave Danhi, owner of the California hospitality recruitment firm dd factor, entered the 2009 Grilled Cheese Invitational last April in Los Angeles. While the well-known L.A. chef didn’t win the trophy, he did walk away with the idea to create The Grilled Cheese Truck.

“Before the contest began, there was already a line [at the event] well over an hour long,” he says. “The number of grilled cheese fanatics was mind boggling.”

Leaving the event, Danhi spotted the Green Truck—a mobile concept that sells local and organic fare. “That’s when the light bulb went off,” he says.

To execute that idea of combining grilled cheese and mobile foodservice, Danhi searched for a partner and a vehicle. By October, he and business partner Michele Grant had the menu perfected and the cheddar-orange truck ready to hit the streets.

“At first I thought, ‘How hard can it be?’” Danhi says. “Well, it’s certainly not any easier than operating a brick-and-mortar restaurant. There’s a whole other layer of problems … mechanical issues like the batteries get drained, the on-board POS system doesn’t work … and you have this finite amount of space. Plus, propane cooks at a different temperature than natural gas, so there was a lot of tweaking to get the sandwiches to melt correctly and the bread browned right.”

Everything on The Grilled Cheese Truck menu is homemade. Prep work, like smoking the ribs for the Cheesy Mac and Rib sandwich, is done at a commissary kitchen.

While the $7.50 Cheesy Mac and Rib sandwich, which combines macaroni and cheese with sharp cheddar, barbecue pork, and caramelized onions, is Danhi’s own invention, the rest of the menu is pretty straightforward. The truck offers the Plain and Simple Melt on French or wheat bread with American cheese for $3, sharp cheddar for $4.25, double cream brie for $5.50, or gruyere for $4.50. The more sophisticated Brie Melt on cranberry walnut bread with sliced pears and honey is $6.75, and smoked turkey can be added for $1 more. A dessert melt, which combines roasted banana purée with Nutella and marshmallow, is $6.

If customers want to be creative, they can customize a grilled cheese with add-ons like barbecue pork, macaroni and cheese, bacon, avocado, red onions, tomatoes, apple slices, or peanut butter. Prices for add-ons range from $0.50 to $2.50.

Sides include a cup of tomato soup for $2.50, a cup of macaroni and cheese for $3.25, or an order of tater tots for $3.75. A “shot” of tomato soup for dipping is available for $0.50.

Beverage choices are limited to soft drinks customers grab from a bin to simplify operations on the truck, which attracts long lines of customers thanks to social networking sites that allow fans to track its location.

“I wanted to do a ‘soft’ opening, but had 2,500 followers on Twitter before we even got the keys to the truck,” Danhi says. “We cleared 13,000 followers in five months. Social media like Twitter and Facebook is nothing short of amazing. But following the Tweets can be a full-time job. We get 500 Tweets a day at the minimum. But the bad thing is, if somebody doesn’t like something, they let everybody know in 30 seconds, so you have to address complaints immediately.”

While some foodservice trucks have issues with finding places to park and sell their eats, The Grilled Cheese Truck is invited to more than 99 percent of the places they’ve set up shop.

“There are a lot of restrictions about where you can set up,” Danhi says. “You can’t be 200 feet from an operating restaurant, which I completely agree with. You also have to have a signed letter on the truck from businesses within 200 feet stating that your employees can use their bathroom.”

The Grilled Cheese Truck has provided sandwiches to office workers, for kids’ birthday parties, at movie studio wrap parties, and for post-reception dining at weddings.

The truck is available for a lunch shift from 11:30 a.m. to 2 p.m., dinner from 6 p.m. to 9 p.m., and also late nights, usually for revelers in need of a sobering snack. Danhi says the truck is not always in service for all three of those periods every day.

There is one Grilled Cheese Truck in operation, and Danhi says they’ve acquired a second truck, which may hit the road soon.

“I had the idea I could do this myself on the side,” he says. “Well, I’ve finally hired enough people to staff the one truck. The idea just exploded.”

Danhi says he has considered franchising The Grilled Cheese Truck concept, but isn’t sure it would work just anywhere.

“The food works really well in this climate,” he says. “But I can’t see people standing in line for 45 minutes in Chicago in the winter for grilled cheese. Maybe we’ll develop a brick-and-mortar storefront down the road. At this point I’m not sure how we want to proceed.”