In a medium bowl, combine all marinade ingredients and mix well.
Add the lamb cubes to the marinade and mix until lamb is evenly coated. Place lamb in a sealable bag, and marinate in the fridge overnight.
Preheat barbeque for direct grilling at high heat 475°F-500°F (246°C-260°C). Oil grill to prevent sticking.
Remove lamb from the marinade and thread the cubes onto the bamboo skewers (2-3 cubes per skewer). Season the lamb skewers with salt and pepper.
Place lamb skewers on the grill and slide foil underneath the bamboo skewers to prevent the sticks from charring. Cook lamb for 2 minutes per side or until nice char marks are achieved.
Remove lamb from grill, allow to cool slightly and serve in pita bread with tzatziki sauce.