Alternate cooking Method: Start by grilling the leg over a medium high direct heat to sear the surface. This will give the meat a crusty surface and add texture. Turn every 5 minutes to sear the surface evenly. On the rotisserie you won’t have to worry about this. Grill over this direct heat for about 15 minutes then move to indirect grilling and cut the temperature down to a medium heat. Watch for flare-ups during the direct grilling phase. The leg of lamb will need about 20 minutes per pound to cook so plan accordingly.