Along with robins, tulips and opening day at Miller Park, a new harbinger of spring exists in Milwaukee. Food trucks return to the streets.

The fleet of kitchens on wheels has been growing the last couple of years, and it reached a critical mass last summer, with new vendors offering everything from grilled cheese sandwiches to pierogies. You could eat Italian, Mexican, vegetarian, Chinese, Asian fusion and plain old American from trucks and trailers parked at curbs.

Among the folks frying, baking and sauteing on board the vehicles is a graduate of Johnson & Wales University, which has one of the most prestigious culinary schools in the country. Ryan Whitman has been executive chef at the high end caterer Gracious Events and Wauwatosa restaurants Bjonda and Firefly Urban Bar & Grill. He is the kitchen consultant behind and general manager of Catch 22, a popular Milwaukee Street lounge and eatery.

But Whitman is also the owner and operator of Red Truck Sliders, a business with a self-explanatory name. Four varieties of sliders – the basic hamburger, a cheeseburger, a bacon burger and a blackened bacon burger with Gorgonzola cheese and creole sauce – were sold in pairs for six bucks last year. Cajun-seasoned fries with a choice of dipping sauces were $3.

Why would a chef with a degree from Johnson & Wales be making sliders on a truck? "I had it in the back of my head before the (food truck) fad broke out," Whitman said last week. "I had always wanted to do something besides the standard restaurant.

"I'm an entrepreneur at heart, and I wanted to do something for fun, not as a full time job. Unlike a bricks and mortar place, a food truck is easy to turn on and turn off.

"I love being outside, and I love talking to people, things you can't do in a restaurant kitchen."

And why sliders? "I was doing them way back at Bjonda, before the fad hit. I called them micro-burgers," he explained.

Whitman spent his early childhood in a Chicago suburb, and he moved with his family to Cedarburg when he was a teenager. He got a job as a dishwasher at the old Boder's on the River in Mequon, and his career path was set.

A string of cooking jobs included Highland House, The Knick and the old Club Forest. While in college Whitman did an internship at Wolfgang Puck's Chicago Spago outlet.

The chef and his wife Marija owned Berkeley's and its successor restaurant, El Guapo, in Whitefish Bay, but those were star-crossed ventures. A promised bank loan fell through when the great recession of 2008 struck, leaving the business under-capitalized, and street construction made customer access to the location difficult. Berkeley's interior designer was killed in an accident before he could execute the job.

Whitman joined the Catch 22 team as its concept was being developed last year. Owner Todd Fogel wanted to offer imaginative bar food, and sliders were on his mind. He was looking for an experienced chef to make that happen.

"It helps in a job interview if you pull up in a slider truck," Whitman said with a grin. He put together a lineup of 22 sliders, sold in multiples of three and six, that includes sushi grade tuna steak with bacon, lettuce and tomato; chicken satay with spicy sesame peanut sauce and ginger cucumber salad; and a fish fry slider served with cole slaw on rye bread.

The Catch 22 menu also features such appetizers as a full-sized quesadilla ($10.95) and vegetable spring rolls served with a sweet ginger dipping sauce ($8.95). Entrees will be soon be added.

Some of the city's food trucks have already hit the streets, but Whitman's red truck needs a few repairs before it is ready to roll. "Part of owning a food truck is you are always fixing things," he said. Look for it next month.

I asked Whitman some questions about mobile restaurants and his own personal food preferences.

OMC: How profitable are food trucks?

Ryan Whitman: Private parties and block parties are a lot better for making money than parking on the street or at the food truck gatherings. People love the novelty of a food truck pulling into their driveway. It's a form of catering.

The weather affects your business if you are just on the street. Plenty of days last summer I took the truck out and lost money. There are expenses every time you take the truck out.

OMC: How did you get your truck?

RW: It's a 1985 Step Van that I converted. I did all the work myself. I put in an astronomical amount of time. It's an old beast.

OMC: How is working on the truck different than in a restaurant kitchen?

RW: Safety is a big issue. There are a hundred ways to die in that thing. We have gasoline and propane on board. You have to worry about carbon monoxide and road hazards.

And the heat inside the truck. It was 120 degrees on one of those days in the 90s last year. I had an employe leave in an ambulance.

OMC: Any changes to your Red Truck Sliders menu this summer?

RW: I'm adding the Carolina (shredded barbecue) pork slider we have at Catch 22 and a vegetarian slider.

OMC: Do you watch any TV cooking shows?

RW: No. They give me anxiety. I feel like I'm at work. And I barely watch any TV.

OMC: What is your dream gig?

RW: I would have a small restaurant with only me and a few employes. We would be very creative. Only seven things on the menu. We would interact with the customers.

The restaurant would be off the radar a little bit. No name on the door. People would know about it only by word of mouth.