In a large stockpot, saute the onions in the vegetable oil over medium heat until translucent (about 5 to 8 minutes). Add the carrots and chicken stock, cover the pot, and bring to a boil. Reduce the heat and simmer for 10 minutes. Add the celery and simmer another 5 minutes, stirring occasionally.
Turn off the heat and stir in the pasta. Cover the pot and let sit for 20 minutes.