How to Make It
Beat egg in a large bowl, add chicken, and coat well. In another bowl, combine 1/3 cup cornstarch with salt and pepper. Transfer chicken with a fork to cornstarch mixture, and stir with a spatula to coat every piece.
Transfer chicken to air-fryer oven racks (or fryer basket, in batches), leaving a little space between pieces. Preheat air-fryer at 400°F for 3 minutes. Add the battered chicken; cook for 12 to 16 minutes, giving things a shake midway. Let dry 3 to 5 minutes. If chicken is still damp on one side, cook for 1 to 2 minutes more.
Whisk together remaining 2 teaspoons cornstarch with broth, soy sauce, ketchup, sugar, and rice vinegar. Heat canola oil and chiles in a large skillet over medium heat. When gently sizzling, add the ginger and garlic; cook until fragrant, about 30 seconds.
Re-whisk cornstarch mixture; stir into mixture in skillet. Increase heat to medium-high. When sauce begins to bubble, add chicken. Stir to coat; cook until sauce thickens and nicely clings to chicken, about 1 1/2 minutes. Turn off heat; stir in 1 tablespoon green onion and sesame oil. Transfer to a serving plate, and top with sesame seeds and remaining 1 tablespoon green onion.