1. in 10 inch skillet, cook bacon over medium heat 8 minutes or until browned, turning once transfer bacon to paper towels to drain discard all but 1 Tbsp of fat from skillet
2. into fat in skillet stir vinegar, sugar, oil, mustard and pepper until blended. heat dressing over medium low heat for 1 minute.
3. in large bowl, toss oranges, chicken and spinach with warm dressing until salad is evenly coated. crumble bacon over salad