I watch as Tarsis Delgado adds a lot of both to the five soft corn tortillas he has already piled with beef, lettuce and salsa. It's a single order. The customer, a slim man in his early twenties wearing a tank top and baggy low-rider shorts, stands waiting. He's clearly anxious to eat, just as I was minutes before, when I pulled up to Delgado's cart parked outside the Maryland Vehicle Administration in Gaithersburg. But after my third taco, I'm stuffed.

The cart, which Delgado and his wife, Nicolasa, call Delgado's Eatery Place, sits among several other similar carts. But if my taco test has accurately measured the relative merits of the selection of vendors, the Delgados' cart packs the biggest and best flavor.

Tacos, made with soft corn tortillas, come in three varieties: chopped beef, shredded chicken or chopped beef tongue (taco lengua), all served with chunky guacamole, freshly chopped cilantro and a wedge of lime, all mounded so generously that their two-ply tortilla base offers scant support. I ate mine with a plastic fork.

Nicolasa Delgado, who cooked at the Grand Hyatt Hotel downtown for 11 years, preps the food. Her husband hawks it. "I'm a 'sell' person," Delgado tells me. The cart sells burritos as well (black beans and rice with either chicken, beef or tongue) and hamburgers and hot dogs.

But tacos are by far the most popular. By Delgado's reckoning, he sells a few hundred tacos a day. Judging by the lines waiting by each vendor, there is plenty of business to go around, but Delgado doesn't want to be in this spot forever. He hopes the nearly two-year-old family business will soon grow from the cart to a truck to a restaurant. "We're not going to get rich, but we're independent," he says.

I'll gladly follow wherever they go.

The Delgado's Eatery Place cart is parked outside the MVA at 15 Metropolitan Grove Rd. (off Clopper Road) in Gaithersburg. Monday through Friday from about 8 a.m. to 5:30 p.m. and Saturday from about 8 a.m.to 4 p.m. Tacos are $2, burritos are $3.50.

-- Matt McMillen

Matt McMillen last wrote for Food about Euro-Latino Grocery in Arlington.

Tarsis Delgado, his daughter Marilyn and Nicolasa Delgado at the family's cart.