Place a soup pot over medium heat + coat with the oil. Add the onion, garlic, carrots, celery, thyme + bay leaf. Cook + stir for about 6 minutes, until the vegetables are softened but not browned.
Pour in the chicken stock + bring to a boil. Add the noodles + simmer for 5 minutes until tender.
Fold in the chicken, + continue to simmer for another couple of minutes to heat through, + until noodles are cooked to al dente.
Add the lemon juice, + season with salt + pepper to taste.
Sprinkle with chopped parsley (if using) before serving.