Remove any excess fat and silver skin from the lamb rack. Ensure the bones are clean and exposed for an impressive presentation. Season with salt and pepper to preference.
In a small bowl, mix the butter or olive oil, garlic, rosemary, thyme, salt, and pepper. Rub the marinade all over the lamb racks, coating every crevice of the lamb. If time permits, let it marinate in the refrigerator for at least an hour or up to 24 hours to deepen the flavor.
Prepare your smoker according to the manufacturer's instructions. Preheat temperature to 225°F (107°C). If you don't have a smoker, you can use a charcoal grill by setting it up for indirect grilling.
If using a smoker, add the wood chips to create smoke. Place the lamb racks directly on the smoker grate. Smoke the lamb rack for about an hour or until the internal temperature reaches the right doneness. A meat thermometer is very helpful because it gives you the exact temperature. Aim for medium rare to medium, 130-135°F (54-57°C) if cooking for a crowd. If not, cook to the desired doneness.
Once the lamb rack is cooked to your preference, remove it from the smoker and let it rest for 10-15 minutes so the juices can redistribute throughout the meat. Slice the rack into individual chops, cutting between the bones.
Serve hot with your choice of sauce.