In a bowl break up all the bread into small pieces. Add the onions, carrots, celery, sage, salt, and pepper.
Mix together the egg and 1 tablespoon of water. Pour onto the bread mixture. Using your hands or a wooden spoon combine well so the bread further breaks up and absorbs the moisture. If still dry add additional water a tablespoon at a time until moist but not runny.
Preheat the smoker to 225 degrees F (107 degrees C); add a chunk of hickory and apple wood.
Prepare the turkey breast by removing any skin or fat. Taking a knife, start cutting the breast in half, but don’t go all the way through (thus butterflying the turkey breast to create a larger, flatter piece of meat).
Layout 5 pieces of string evenly on a chopping board then place the turkey evenly over it.
Place the stuffing evenly across the center of the turkey. Gently roll the turkey making sure not to push too hard otherwise the stuffing will be squeezed out.
Starting at one end, gently tie the twine around the turkey breast. The twine is just to help the meat hold its shape and does not need to be very tight.
Sprinkle the turkey breast with the herb rub.
Add the turkey roll to the preheated smoker and cook for 3 hours. The turkey is ready when it is at 165 degrees F (74 degrees C).