Heat oil in a large nonstick skillet over medium-high heat. Add onion, carrot, and celery. Sauté 6 to 8 minutes or until tender. Add bay leaves; sauté 1 minute.
Add chicken broth and water; bring to a boil. Stir in orzo; cook, uncovered, 8 minutes. Reduce heat, and stir in chicken. Simmer 5 to 6 minutes or until chicken is done. Stir in spinach; remove from heat. Let stand 2 to 3 minutes or until spinach wilts. Stir in parsley, oregano, lemon juice, pepper, and salt. Remove bay leaves. Serve immediately.
Note: You may need to add extra broth or water when reheating.