Place chicken and flour into a large container with a lid. Secure the lid and shake well until the chicken is evenly coated.
Crack in the egg, add soy sauce and sriracha, then replace the lid and shake again until combined and the chicken is coated.
Add breadcrumbs, secure the lid and give everything one final shake until the chicken is evenly coated in crumbs.
Heat a generous drizzle of oil in a large frypan over medium heat. Add chicken in a single layer and cook for 3–4 minutes on each side, or until golden, crispy and cooked through. Work in batches if needed. Remove from pan and set aside.
Meanwhile, whisk together Kewpie mayonnaise, sweet chilli sauce, rice wine vinegar and sriracha in a large bowl until smooth and creamy.
Add the crispy chicken to the sauce and toss until evenly coated. Transfer to a serving plate and finish with sesame seeds and freshly chopped chives.
