Prepare the sauce by combining all the sauce ingredients together. Set aside.Cut each chicken breast in half lengthwise (I butterfly first to make it easier) so you end up with four pieces of chicken.Prepare 3 bowls - one with the egg, another with breadcrumbs, and the third with flour. Start with small amounts of breadcrumbs and flour and add more as needed.Heat 1/4" of peanut oil in a heavy skillet on medium-high heat.One by one, dip each piece of chicken in the flour, then the egg mixture, and finally the breadcrumbs. Add each piece to the pan and cook for about 4-5 minutes per side or until the chicken is cooked through and the breading is golden brown.Remove the chicken to a paper towel lined plate. If you want to toast the inside of the buns, simply place them in the same pan you cooked the chicken in for a couple of minutes.Assemble the sandwiches and enjoy!