Preheat smoker to 225 degrees Fahrenheit with a water pan for moisture placed in the smoker.
Prep lamb by trimming excess fat, rinse in cold water, and pat dry. Inject lamb with apple cider vinegar; it’s normal to see the lamb swell slightly. For a five pound lamb you’ll use roughly one cup (you don’t need much).
Pat dry and then rub all over with olive oil, salt, pepper and rosemary. Tie tightly with kitchen twine.
Place uncovered on smoker for an hour. After the first hour spritz every 15 minutes until the internal temperature reads 165 degrees. This may be roughly three hours. Go by temperature not time.
At 165 degrees wrap the lamb in foil tightly and place back on smoker until the internal temperature reads 195 degrees or the consistency as you insert the thermometer is like butter (gliding in and out smoothly).
Remove from smoker and place in a clean cooler (with no ice) and let rest for at least an hour. Then remove and shred for your favorite dish.