1. Preheat broiler or prepare a medium-hot charcoal fire.
2. Make sauce: Combine soy sauce, cilantro, lime juice, oil, sugar and 1 Tbsp. water in a small bowl. Mix well until sugar is dissolved. Refrigerate until ready to serve. Sauce can be prepared up to 2 days in advance and stored, covered, in the refrigerator.
3. Make shrimp: Rinse shrimp under cold running water, drain and pat dry. Place them in a large bowl and add lemon juice and zest, oil, garlic, salt and pepper. Mix well to coat. Thread shrimp flat (through tail and head) dividing evenly among 8 long metal skewers. Cook shrimp about 6 inches from heat until bright pink and firm, about 3 minutes per side. Remove shrimp from skewers to a serving platter and serve warm with sauce on the side.