If you are looking to do TX style smoked turkey it will generally be done off the bone. If you can't find just the breast then cut off before brine/smoking. Here is my method:
1) Get large boneless breast from the butcher or buy breast on the bone or buy whole turkey. NEVER buy the butterball boneless turkey breast. It’s packed full of so much sodium and other stuff it really changes the flavor.
2) If still on the bone, remove.
3) Brine overnight in a basic brine.
Brine ratio:
1 gal cold water
1/2 cup kosher
2/3 cup brown sugar.
4) Pull breast, rinse and sprinkle with rub.
Rub ratio:
2 tbsp coarse pepper
1 tbsp kosher
1/2 tsp garlic powder
1/2 tsp onion powder
(Makes more than you need)
5) Smoke 275 with oak wood until around 150 or about 2 hrs
6) Lay double layer of foil, 1/4 stick butter on foil, breast top side down on butter, place another 1/4 stick on top and wrap. Return to smoker.
(I had one breast where the rub got washed off so placed top side up last time)
7) Pull when 160. Leave in foil and rest for 30 min -1 hr minimum. Can remain wrapped in cooler all day. Do not let temp drop below 140
8) Carve against grain about pinky thick. Drizzle butter from foil on top and serve.