Preheat oven to 375 degrees F.
Place sweet potato cubes onto a baking sheet and toss with olive oil, salt and garlic. Roast 30-35 minutes, turning once with a spatula, or until potatoes are cooked through and begin to brown. Remove from oven and set aside (this can be done a day ahead).
Place pecans in a foil pie pan and place in oven still warm from the potatoes. Turn off heat and let pecans toast in turned-off oven about 15 minutes, until they turn golden brown and smell fragrant. Remove from oven to cool.
Cook rice according to package directions, omitting salt and fat. Set aside to cool.
In a large mixing bowl, combine sweet potatoes, pecans, rice, carrots, celery, cranberries and onion. Stir to mix well. Sprinkle vinegar, olive oil, soy sauce, orange peel and black pepper over salad mixture and stir so that salad absorbs dressing. Serve at once, or chill and serve later.
Per serving: 280 calories, 12 g fat (1 g saturated), 0 cholesterol, 38 g carbohydrate, 111 mg sodium.