To prepare a tenderstem and chicken vietnamese noodle soup recipe, you'll first need to gather your ingredients. To this point, I'm going to be using chicken, but you could also use beef, pork, or beef tenderloin. If you don't have any of these ingredients on hand, then you can substitute beef or pork for the chicken. Heat 2 tablespoons of vegetable oil over medium-high heat. Add the onion and cook until translucent, about 5 minutes. Stir in the carrots and celery. Cook, stirring occasionally, until the vegetables are just tender, 3 to 4 minutes, scraping up any browned bits from the bottom of the pan. Pour the broth into the pot and bring it to boil. Reduce the heat and simmer the soup for 1 to 2 hours.