Trim the lamb of any sinew, gristle or bone but leave the fat.
Combine 8 cups water, both salts, the sugar, bourdon, syrup, cloves, juniper, bay leave and thyme in a saucepot over high heat. Bring to a boil and wisk to make sure the salt and sugar dissolves; this will be the brine. Remove from the heat and cool to room temperature over an ice bath.
Place the lamb into the curing brine, using a plate as a weight if necessary to ensure that the lamb is fully submerged. Cure overnight and no more than 14 hours in the fridge.
Remove the lamb from the cure and pat dry, removing any herbs or spices. Leave uncovered at room temperature for 30 minutes.
Roll the lamb into a uniform cylinder, fat-side out, and secure tightly with butcher's twine.
Prepare a smoker. Smoke the lamb until the internal temperature of 155 degrees F is reached.