A longtime reader who I met when his wife took a cooking class from me, Ken retired to Hawaii several years ago. Recently he wrote to say he thought we needed some Hawaiian recipes in the American Regional Recipes section of The Perfect Pantry, and to help me get started, he sent several locally-published cookbooks. Hawaiian cuisine is really a crossroads of all of the cultures who've settled on the islands: Asian, Polynesian, native Hawaiian, and many former military folks from all around the United States. I've been having a great time reading through the books, marking all of the dishes I want to try. It's almost impossible to get authentic Hawaiian ingredients here in New England; however, many recipes can be adapted to what's locally available, like this one, which calls for Okinawan sweet potatoes. A bit of research taught me that Okinawan potatoes are a particular variety -- with purple flesh! I substituted our regular sweet potatoes, which I know everyone can buy in the market. Make this potato salad several hours ahead, to allow the flavors to blend, and serve it as a side dish with grilled beef, pork or chicken.