RALEIGH, N.C.—When Oliver Williams moved here in 1961, a steak place was his main option for a fancy meal.

Now, the population in Raleigh and surrounding Wake County tops a million people, buoyed by high-tech companies and a dozen universities. And Mr. Williams marveled last week at his choice of restaurants, among them a Laotian hot spot called Bida Manda and a nearby Lebanese restaurant called Sitti.

Diversity,...