In a bowl, mix mayonnaise, Thai sweet chili sauce, Sriracha, and honey to make the bang bang sauce. Set aside.
Place the chicken tenderloins in a bowl with buttermilk, and let marinate for 10 minutes.
In another bowl, whisk together flour, cornstarch, egg, Sriracha, garlic powder, kosher salt, black pepper, and cayenne pepper if using.
Dip each chicken tenderloin into the flour mixture, then coat with panko breadcrumbs.
Heat canola oil in a large skillet over medium-high heat.
Fry the chicken tenderloins until golden brown and cooked through, about 3-4 minutes per side.
Remove chicken and drain on paper towels.
Toss the fried chicken in the bang bang sauce or serve the sauce on the side.
Garnish with chopped parsley and serve immediately.