Heat avocado oil in a large cast iron skillet over medium high heat.
Pound the chicken to 1 inch thickness.
Lightly season the chicken breasts with salt and pepper.
Sear the chicken in the skillet for 4-5 minutes per side, being sure to leave the chicken in place long enough to develop a golden sear on each side. Cook to internal temperature of 165℉. Once cooked, remove from the pan to a clean plate and tent with foil to allow the chicken to rest.
Slice the Italian bread in half, brush the olive oil dip on the inside of the top and bottom of the bread. Place the chicken breasts on the bread.
Top the chicken with fresh mozzarella, tomato slices, and basil leaves. Place the top of the bread on the sandwich.
Cut to serve four sandwiches and serve immediately.