1. Pour 2 inches oil into a large, heavy-bottomed pot (to ensure safe frying, pot should not be more than one-third full). Heat over medium-high until a deep-fry thermometer reads 320 degrees. Reduce heat to medium to maintain temperature. Meanwhile, combine cornstarch, 2 teaspoons salt, and 1/4 teaspoon pepper in a large resealable plastic or brown paper bag. Add wings, seal or fold bag closed, and shake vigorously to evenly coat.

2. With a Japanese spider or slotted spoon, add one-third of wings to oil, stirring a few times, until cooked through and oil returns to 320 degrees, 6 to 8 minutes. Transfer to a wire rack set on a rimmed baking sheet. Fry remaining wings in two batches. Let cool completely, 15 minutes. Meanwhile, combine soy sauce, Sriracha, garlic, ginger, sugar, vinegar, and 1/2 teaspoon pepper in a saucepan. Bring to a boil, stirring until sugar dissolves; cook until reduced to 3/4 cup, 8 to 10 minutes.

3. Increase heat to medium-high and bring oil in pot to 380 degrees. Return one-third of wings to oil, stirring occasionally, 5 to 7 minutes. Return to rack-lined baking sheet; let excess oil drain to prevent sogginess, 30 seconds. In a large bowl, toss with one-third of soy-sauce mixture; sprinkle with sesame seeds and serve immediately with kimchi. Fry remaining wings in two batches, returning oil to 380 degrees in between. To serve all batches at once, keep wings warm on rack in a 225-degree oven, and toss in sauce all together at end.