In a large bowl, combine the red wine, red wine vinegar, pomegranate molasses, olive oil, salt, sugar, black pepper, coriander, oregano, garlic cloves, and onion. Place the lamb cubes in a non-reactive container or large ziplock bag and cover with the marinade. Refrigerate and allow to marinate for at least 6 hours, but no longer than 14 hours.

Remove meat from the marinade, discarding all solids. Thread the meat cubes onto heavy, flat metal skewers (6-8 cubes per skewer) and season with salt and pepper.

Grill over medium-high heat for 7-8 minutes per side rotating them as needed until cooked through and evenly charred on all sides.

Serve immediately with sliced raw onion and pomegranate molasses and adjika (Georgian pepper paste) for dipping.