Cut the boneless chicken into 1 inch bite sized pieces.
Mix together all the ingredients under marinade and rub all over the chicken. Marinate for at least half an hour.
Season the flour and panko breadcrumbs for coating with salt and pepper.
To start making popcorn chicken, arrange an assembly line of sorts. Place flour, buttermilk and breadcrumbs next to each other along with the chicken. Arrange a wire rack to place the chicken once crumb coated.
Now start by lightly coating the chicken with flour. Dip it in buttermilk next, and then coat with breadcrumbs. Repeat for each piece of chicken, and keep placing them on the wire rack.
Heat oil for frying and deep fry in batches on medium heat till the chicken is cooked through and lightly brown on the outside.
In the meanwhile, mix together all the ingredients under spice mix.
Dust the chicken pieces with the spice mix as soon as they are fried. This helps coat the mixture all over the chicken. I usually sprinkle the spicy mix and toss the chicken in it while it's still hot. Serve hot with some sriracha mayo dipping sauce or schezwan sauce.