Soak 8 wooden skewers in water for one hour.
In a food processor combine the cilantro, parsley, scallions, garlic, and lime juice and puree until finely chopped. Add the yogurt and sour cream and continue pureeing until smooth. Season to taste with salt and pepper.
Preheat charcoal grill or grill pan.
In a small bowl stir together the olive oil, garlic and gingerroot. Arrange the vegetables on the 12 skewers and baste with the olive oil mixture. Season with salt and pepper. Grill the vegetables, basting occasionally, until browned and tender, about 8 to 10 minutes. Serve with the cilantro sauce.