In a large soup pot, heat olive oil on medium high.
Add carrots and celery and cook for 4-5 minutes on medium.
Add chicken broth.
Add ground thyme, salt and pepper.
Add chicken and fresh thyme.
Bring to boil.
Add orzo and cook for 7-11 minutes until pasta is cooked.
Add lemon zest and juice.
Serve with a slice of lemon and fresh thyme as a garnish.