1. Sauté onion in 1 Tbsp. hot oil in a medium skillet over medium heat, stirring often, 8 minutes or until caramel colored. Add 2 Tbsp. vinegar, stirring to loosen particles from bottom of skillet. Remove from heat; cool 5 minutes.
2. Process onion mixture, honey, next 3 ingredients, and remaining oil and vinegar in a blender 30 seconds or until blended. Cover and chill 3 to 24 hours.