Preheat oven at 350°F (180°C). Place pecans on a cookie sheet and toast them for 10 minutes. While pecans are toasting, combine sugar, oil, salt and spices. Remove pecans from oven and toss with sugar mixture until well coated. Return to the oven and roast pecans 8 – 10 minutes more or until the coating is dry. Remove from oven. Reserve. Pecans can be prepared several days ahead and stored in an airtight container.
Sauté bacon in a medium skillet until crisp. Leave bacon in skillet and spoon off excess fat. Add onions and cook until tender. Stir in mustard and cook 1 minute longer. Whisk in apple juice, oil and vinegar. Season with salt and pepper. Keep dressing warm until ready to serve. Dressing can be prepared two days ahead and kept refrigerated. Warm dressing before using.
Before serving, toss greens with pear, blue cheese and pecans with some of the warm dressing. Serve salad immediately.