Heat the oil in a saucepan over medium heat. Add onion; cook 8 minutes or until soft, stirring frequently. Stir in thyme and garlic; cook 2 minutes, stirring frequently. Stir in wine and vinegar. Bring to a boil; reduce heat, and cook 8 minutes or until most of liquid evaporates, stirring occasionally.
Place the onion mixture in a food processor. Add the olives and the black pepper, and process until smooth, scraping down the sides of bowl.