Essentially, fried chicken tenders marinated in and then coated with a fiery mustard-based sauce. The chicken is really just a vehicle for the sauce. Recipe shamelessly copied from America's Test Kitchen cookbook.
Whisk all sauce ingredients together and set aside.
Cover chicken with plastic wrap and pound to an 1/2-inch thickness. Slice breasts in half and transfer to a large plastic bag. Add 1/4 cup sauce, seal bag and squeeze gently to coat chicken with sauce. Refrigerate for at least 30 minutes and up to 2 hours.
Meanwhile, combine flour, cornstarch, salt and baking powder in a large bowl. Add 6 tablespoons of the sauce and, using your hands, blend until mixture resembles coarse wet sand.
In another bowl, whisk egg whites until foamy.
Set a large wire rack on a large baking sheet.
Remove chicken pieces from marinade and pat dry with paper towels. Dip each piece in the egg whites and transfer to flour mixture, pressing lightly to adhere. Place on wire rack. Repeat with other chicken strips. Cover and refrigerate for 15 minutes (up to 4 hours).
Heat oil in a large skillet over medium-high heat until oil shimmers. Add 1/2 of the chicken strips and fry until golden brown, 2-4 minutes per side. Remove to paper-towel lined platter and keep warm. Fry remaining chicken strips.
Serve at once with remaining mustard sauce for generous dipping and a box of tissues for nose-blowing as the sauce clears everyone's sinuses.