Soak six 12-inch bamboo skewers in warm water for 30 minutes. Thread the chicken onto the skewers and set in a shallow glass baking dish.
On a cutting board, use the side of a large knife to mash the garlic, ginger and salt to a paste. In a bowl, whisk the paste with the yogurt, mustard oil, lemon juice, cumin, mace, nutmeg, cardamom, turmeric, cayenne and black pepper. Pour the marinade over the chicken; turn to coat. Cover and refrigerate for 3 to 4 hours, turning occasionally.
Light a grill. Lightly oil the grate. Grill the chicken over a medium-hot fire for about 4 minutes per side, or until it is cooked through and golden. Serve with the lemon wedges, red onion, cilantro and Cucumber Raita.