Prepare Chicken: Cut chicken breast into small squares and submerge in buttermilk. Let it sit for a couple of hours.
Strain Buttermilk: Strain off the buttermilk from the chicken.
Prepare Dredge: Mix all-purpose flour, corn or rice starch, kosher salt, Lawry's seasoning, smoked paprika, onion powder, garlic powder, mustard powder, and black pepper in a bowl.
Dredge Chicken: Coat the chicken in the flour mixture.
Egg Wash: Dip the dredged chicken into beaten egg whites.
Final Coating: Mix Panko breadcrumbs with stripped thyme and coat the chicken.
Fry Chicken: Fry the chicken in small batches at 350°F for 4 minutes.
Drain and Season: Drain the chicken and season with a little black pepper.
Serve: Plate the popcorn chicken and serve with homemade barbecue sauce.