1. Preheat oven to 350°. Bake pecans in a single layer in a shallow pan 8 to 10 minutes or until toasted and fragrant.
2. Prepare rice according to package directions; let cool completely (about 25 minutes). Stir in cranberries, celery, green onions, and toasted pecans.
3. Whisk together canned pumpkin, next 5 ingredients, and 2 Tbsp. water. Gradually whisk in olive oil in a slow, steady stream, whisking until blended.
4. Pour pumpkin vinaigrette over rice mixture; stir gently to coat. Cover and chill 2 to 24 hours. Serve at room temperature.