Most think of roasting when considering how to make rack of lamb. Roasting is a great way to cook an elegant lamb dinner but the meat benefits more from the fire. Everything from the delicate flavor of lamb to its subtle gaminess and tender meat gets better when grilled. This BBQ rack of lamb is simply seasoned with mustard, salt, and black pepper before it is grilled. During this time it gets tender, a bit smoky, the fat renders into the meat and once cooked to a perfect medium-rare, it is served with a delicious compound butter consisting of butter (of course), garlic, fresh herbs and a touch of lemon zest for brightness. The compound butter should be nice and firm so quickly mix the ingredients and refrigerate so it has time to chill before the BBQ rack of lamb is complete. Few things are more indulgent than having a rich, flavorful knob of cold butter melt and further enhance a juicy lamb chop.