Combine all the rub ingredients in a food processor and blend until it forms a coarse paste. Butterfly open the leg of lamb and spread an even, thin layer of the rub. Wrap around the rotisserie spit, tie with butchers twine until tightly and evenly wrapped, then spread more of the rub over the outside.
Place the spit spikes on to hold the meat in place while it spins, insert a MEATER plus probe thermometer into the center. Place on the rotisserie with a foil tray underneath and cook until the thermometer hits 135 degrees. Let rest for 10-15 minutes before slicing and serving warm. Finish with a drizzle of fresh lemon juice over top if desired.