Heat the oil in a medium saucepan until warm.
Add the onion and cook for 5 minutes, or until soft. Add the remaining vegetables and cook until tender.
Add the thyme and chicken stock and bring to a boil. Reduce heat so that the soup simmers; cook for 20 minutes.
Season with salt and pepper.
Bring stock to re-boil, add the egg noodles, and cook for 7 minutes, or until the noodles reach the desired tenderness.
Chop the seared chicken breast into ½-inch pieces and add to the soup.
Serve in warm bowls.