1. Heat gas grill to medium high or prepare charcoal grill with medium-hot coals or heat broiler.Marinade:
2. In a medium-size bowl, whisk together hoisin sauce, soy sauce, vinegar, lime juice, chopped ginger and chili paste until blended. Set aside.Kebabs:
3. Place sweet potato slices in a microwave-safe dish large enough to hold them in a single layer. Add 1/4 cup water. Cover with plastic wrap and vent at one corner. Microwave on high for 5 minutes, rotating dish halfway through cooking.
4. Thread the sweet potatoes on 2-12-inch-long metal skewers. Repeat with pork slices and zucchini slices, each on 2 separate skewers. Use additional skewers if needed.
5. Reserve 1/4 cup of the marinade. Brush both sides of skewers liberally with the remaining marinade and allow to marinate at room temperature for 15 minutes.
6. Place sweet potato and zucchini skewers on grill. Turn both potato and zucchini skewers after 4 minutes. Cook sweet potatoes 2 more minutes; remove to platter and cover with foil. Cook zucchini 6 more minutes; remove to platter. Add pork skewers and cook 8 minutes total, turning halfway.
7. Just before serving, use clean brush to brush all skewers with the reserved 1/4 cup marinade. Makes 6 servings.