In your stock pot, sauté the celery, carrots, and onion with the butter and oil for 5-7 minutes.
Stir in the garlic and cook for about 30 seconds. Add in the flour and cook for another minute or so.
Add in the chicken broth and stir until the flour has dissolved, then add the Italian seasoning and chicken. Bring to a boil.
Cover with lid slightly ajar and reduce to a simmer for 15 minutes.
Stir in the orzo. Cook with no lid for 10 minutes or until the orzo is cooked through. Stir often to to prevent the orzo from sticking to the bottom of the pot.
Remove the chicken and cut up or shred. Add it back in along with the lemon juice and parsley. Season soup with salt & pepper to taste. Serves 6.