Heat oil n a saucepan over medium heat. Add onion and cook, stirring often, until onion is translucent. Add garlic and cook for 2 minutes more. Add vinegar, wine, preserves and chipotle. Increase heat to medium-high and bring to a boil. Reduce heat to medium and simmer until liquid is reduced to about 1/3 cup. While continuing to reduce sauce, stir in cornstarch mixture until thickened. Season with salt and pepper.