For the marinade, combine all ingredients in a mixing bowl, setting aside one cup. Put the remaining marinade in a sealable plastic bag. Cut the lamb into 1" squares and marinate for at least 4 hours in the refrigerator. Marinating longer is even better. Turn the bag over several times during the marinating process to ensure the meat is well covered!
Soak skewers for at least 20 minutes in water so they don't burn. Preheat the grill as you make your skewers. Start with veggie kabobs - keep lamb separate as they need longer to cook. For a beautiful presentation, alternate veggies to create a colorful kabob. You can also use pineapple, which turns ultra sweet on the grill. Drizzle the reserved cup of marinade over the veggies. Next, skewer the lamb, alternating red onion between each piece of meat, and discard the bag of marinade.
On a medium hot grill, cook the veggie kabobs until slightly charred, there should still be a little crunch to them. For the lamb, vary the amount of barbecue time for your own preference. Hint: for lamb, the trick is to NOT overcook it. Well done lamb tends to be dry and tough.