Grilled Pork Kebabs with Ginger Molasses Barbecue Sauce

Name: Grilled Pork Kebabs with Ginger Molasses Barbecue Sauce
Ingredients: 6 tablespoons cider vinegar; 2 tablespoons sugar; 2 tablespoons ketchup; 1 1/2 tablespoons molasses (regular or robust; not blackstrap); 1 tablespoon minced garlic; 1 tablespoon minced fresh serrano or other small hot green chile (1 or 2), including seeds; 1/2 tablespoon minced peeled fresh ginger; 1/2 teaspoon salt; 1 (1-lb) pork tenderloin, trimmed; 1/4 teaspoon salt; about 30 (8-inch) wooden skewers, soaked in water for 30 minutes