In a large Ziploc bag (or a non-reactive storage dish), combine the ingredients (except for the rosemary you are using for garnish) for the lamb and toss to combine.

Seal; refrigerate for at least 1 hour or up to 12 hours.

When you are ready to cook, preheat an indoor grill (or the oven to 425 F); alternatively, you can barbecue these outside on a grill.

Thread lamb pieces, alternatively with onion, onto skewers (if you find rosemary that has long enough stalk, you can skewer them directly onto the rosemary stalk!!); discard marinade.

Grill lamb until lightly charred and cooked to your liking, turning skewers occasionally throughout cooking, about 8 to 10 minutes total (cooking time will vary depending on the thickness of your lamb and your desired doneness)

Transfer skewers to plate.

If you are using wooden skewers, tuck in a sprig of rosemary in the top of each skewer to mimic the look that the meat is skewered directly on the rosemary stalk