Heat the oil in a medium skillet over medium heat. Add the garlic and cook until fragrant, about 1 minute. Add the marmalade, chipotles, cumin, ½ teaspoon salt, and ¼ teaspoon pepper and bring to a simmer. Cook, stirring often, until slightly thickened, 3 to 5 minutes. Stir in the vinegar.
Reserve half the sauce for dipping, if desired. Cook 1½ to 2 pounds of beef, pork, poultry, lamb, seafood, or tofu on a preheated grill to desired doneness. Brush on the sauce during the last 2 to 3 minutes of cooking.