Combine the onion, garlic, thyme, rosemary, oil, and habanero (if using) in a large bowl.
Season the lamb cubes with the black pepper and 2 tsp of salt. Add to the onion mixture and mix until well coated. Cover and refrigerate for at least 4 hours.
Lightly oil grill or grill pan and preheat to medium.
In a medium bowl, stir together the yogurt, parmesan cheese, basil, cumin, grated garlic, and 1/2 tsp salt. Mix until well combined. Set aside.
Thread the marinated lamb cubes onto 12 skewers (if using wooden skewers, soak them beforehand).
Grill the skewers for 3-4 minutes on each side, until the meat is evenly cooked and slightly charred.
