I didn’t taste my first Taiwanese oyster omelet—a Taiwanese street food classic—in Taipei. Sadly, I’ve never been there. My first encounter with this extraordinary dish occurred in a frantic underground corridor in the New York subway system. Passing a small stall, I watched a chef toss oysters with eggs, add a sweet ketchup sauce, and flip it onto a paper plate. It seemed so incongruous in that setting that I simply had to try it.It was love at first bite. I was enchanted by the way the softness of the eggs danced up against the deliciously briny slipperiness of oysters. But what made the oyster omelet so special was the way the oysters and eggs were swept away by a mysterious and deliciously sticky substance. It was like a musical composition—each note different—and I found myself taking one bite and then another as I tried to tease out the flavors.I couldn’t stop thinking about that dish, and I found myself dredging up excuses to use that particular subway. But one day, as I sat in that frenzied airless space with busy commuters hurtling past me, it hit me that I’d much prefer eating in the quiet of my own kitchen.But what was the mystery substance? It turns out that the secret ingredient is sweet potato starch, one of the staples of the Taiwanese kitchen. It adds a wonderful textural note to the omelet, and I’ve loved playing around with it in this recipe. I also discovered that this wonderful combination of flavors tastes even better made with small, freshly shucked oysters.If you want to save a little time, instead of making your own, you can pick up some sweet chili sauce from your local Asian market; there are dozens of brands. My recipe is really easy and makes more than you need, but it keeps forever in the refrigerator.