I had been to Hawaii before, watching the whales, lounging at the luaus and basking on white sand. But this time, I was in Honolulu to retrieve my son, who was coming home to Minnesota after four years of college. Between helping sell his surfboard and thanking the benevolent grandmother who baked him mango bread, I realized he knew a side of this place I'd never seen sipping Mai-Tais by the pool.

We had a few days before returning, so I made a request: Show me your Hawaii. Little did I know that curiosity would lead to obsession.

We headed to Hanauma, a secluded snorkeling cove about 10 miles from Waikiki. As we flip-flopped back to the car at lunchtime, I wistfully recalled the umbrella-fronted Greek restaurant we'd passed that morning. My son, however, pointed to the locals' solution for a growling stomach: a lunch wagon, Hawaii's beloved meals on wheels.

Around a gathering crowd, I strained to read the marker board. Today's special? Same as every day: "da plate lunch." A longtime local favorite, this salute to American and Asian starches included rice, macaroni salad, various options for gravy-smothered entrées and pickled cabbage on the side -- all unceremoniously handed to us in a Styrofoam box.

Ono kine grindz (Hawaiian pidgin for delicious local food) can also include the more exotic, such as Kalua Pig, Deep-Fried Mahi-Mahi, Shoyu Chicken, Lau-Lau (pork and fish steamed in taro leaves), Teppanyaki Steak, Grilled Ahi and Crab-Stuffed Salmon.

And who could pass up the Spam Musubi, fried Spam served sushi-style atop a block of sticky rice and wrapped with seaweed?

Delicious food, cheap

There are 362 licensed lunch wagons throughout the islands, 266 on Oahu alone. They reflect a mélange of immigrant heritage from Japanese to Portuguese, but the formula is always the same: good food, fast and affordable. The entrepreneurial concept is said to have evolved from the bento -- the box or bucket of rice, meat and pickled vegetables that Japanese workers enjoyed long ago in plantation fields. The first lunch wagons sprang up as a convenient alternative to bento from home, later expanding to fulfill demand during World War II among dock workers and those disenchanted with military cuisine.

Today, the tradition continues, devoid of pretense and high on comfort food flavor. Although heavily regulated by the Health Department (proprietors must abide by a reported 125 pages of rules), there are few similarities to fast-food chains. For starters, hours are limited; most open midmorning and close by early afternoon, or when the food runs out.

A lunch wagon's marketing is often the first clue of the creativity to come. From wall-to-wall graffiti to highly colorful murals, the typical lunch wagon advertising plan goes no further than the vehicle's four sides. But given what's inside, there's little need for a flight of prime-time radio ads. It's the food that draws people to the counter day after day.

Don't expect an AAA guidebook or soaring arches to point you to your culinary experience. But then, finding Hawaii's lunch wagons is a reward in itself. Some are semipermanent, while others roll up each day to greet their hungry fans. The best way to start the adventure is to go a bit beyond (in some cases, a lot beyond) the tourist routes and ask local residents for recommendations. Or you can simply take a ride and keep your eyes open.

A drive for doughnuts

My lunch wagon ordering skills well honed, we headed off the next day to Haleiwa on Oahu's North Shore, home to the island's most legendary waves. In this quaint surfing town, Main Street alone is well worth the hour-plus drive from Honolulu. Between the board shops, we rummaged through amazing recycled-sari sarongs at Bali Moon, making a quick stop at ground zero for shave ice: Matsumoto's. My real search was fulfilled, however, as Haleiwa's guerrilla gastronomy began to emerge.

Malfrita's Malasadas, which serves addictive Portuguese doughnuts, drew traffic from a grocery store parking lot, while Hono's, Giovanni's and Macky's competed for top honors in fresh shrimp. We had to try them all. The definite standout was Opal Thai Food, ironically situated within view of a McDonald's.

Thailand natives Opel and Aoy Sirichandhra's extensive offerings included Green Papaya Salad and Roasted Chili Shrimp, all made to order in their wagon under a banyan tree. The couple began their Hawaiian culinary journey in a 10-by-10-foot tent, moved to California to save money for a bigger business and eventually returned with lunch wagon and recipes in hand. As at most wagons, customers begin lining up soon after the window opens.

In the past, I would have driven right by this culinary outpost. As each visit to a lunch wagon proved, however, some of the most interesting experiences really do go unnoticed to all but the locals -- or those who like to pretend they are.

Carol Russell, a writer and frequent traveler, lives in Minneapolis.