Bring a large pot of water to a boil and cook tortellini according to package directions, being careful not to overcook. Rinse with cool water and drain well. Set aside.
Meanwhile, preheat oven to 375 degrees. Place bacon on a foil lined, rimmed baking sheet. Bake for 15 to 18 minutes or till browned and crisp. Transfer cooked bacon to paper towels to drain. Crumble and set aside.
In a large serving bowl, combine the broccoli, cooked and cooled tortellini, onion, and dried cranberries. In a small bowl, stir together the light mayonnaise, light sour cream, balsamic vinegar, and sugar. Pour over broccoli mixture, and toss until well mixed. Refrigerate for at least two hours or up to six hours.
When ready to serve, stir in the crumbled bacon and chopped walnuts.