Combine all stock ingredients into a large pot on medium heat. I boiled all my ingredients together for 1.5 hours. Remove all boiled items (chicken, carrots, celery, onion) and place aside. Drain stock into another pot using a fine sieve. This will ensure that the broth comes out clear and removes any chicken bits.
At this point you can save the stock for when you need it. When you're ready to use the stock, bring it to a boil. Once the stock is boiling, add the tortellini. Cook the tortellini until they are soft, but not to the point that they fall apart.
Ladle into a bowl and serve!