Heat the grill to high. Assemble 4 long skewers, alternating 5 lamb cubes with 2 lemon wedges on each. Arrange the skewers in a nonmetallic dish.
In a small bowl, whisk together the oil, lemon juice and garlic. Pour the marinade over the skewers; turn to coat. Let stand for at least 5 minutes (or cover and refrigerate overnight, turning occasionally). Season with salt and pepper.
Lightly oil the grates. Place the skewers on the grill; cover the grill, and cook, turning occasionally, until grill marks are visible and the meat is cooked to the desired doneness, 1 to 2 minutes per side for medium-rare.
Serve the kebabs with sauce and garnish with parsley sprigs, if desired.