Prepare a whole large brisket by rubbing with favorite spices or none at all. Put fat-side up on rack in smoker over mesquite or pecan chips. Smoke for 4 to 6 hours depending on size. Take off smoker and rub generously with Apple Cider Vinegar and wrap well in heavy aluminum foil. Place on sheet and then in a 250 degree oven for 4 to 6 hours depending on size and check periodically to see if tender. Do not overcook in oven.