Prepare the Ingredients:

1. Heat olive oil in a large pot over medium heat.
2. Add the diced onion and garlic, and sauté until translucent.

Cook the Vegetables:

1. Add the sliced carrots and celery to the pot. Cook for about 5 minutes, until they start to soften.

Add the Chicken and Broth:

1. Place the chicken breasts or thighs in the pot.
2. Pour in the chicken broth, and bring to a boil. Reduce heat and simmer for 15-20 minutes, until the chicken is cooked through.

Add the Orzo and Lemon:

1. Remove the chicken from the pot and shred or dice it.
2. Add the orzo pasta to the pot and cook according to package instructions, usually about 8 minutes.
3. Return the shredded chicken to the pot.
4. Stir in the lemon juice, lemon zest, thyme, oregano, salt, and pepper. Adjust seasoning as needed.

Serve:

• Ladle the soup into bowls and garnish with fresh parsley and lemon slices, if desired.