Season chicken breasts generously with salt and black pepper. In a large pot or Dutch oven, heat 1 tablespoon of olive oil over medium-high heat. Add the chicken breasts and sear for 3-4 minutes per side, until lightly browned. The chicken does not need to be cooked through at this stage. Remove chicken from the pot and set aside on a plate.

Reduce heat to medium. Add the remaining 1 tablespoon of olive oil to the pot. Add diced onion, carrots, and celery. Sauté for 5-7 minutes, stirring occasionally, until vegetables begin to soften. Add the minced garlic and cook for another minute until fragrant.

Pour in the chicken broth and scrape up any browned bits from the bottom of the pot. Add the bay leaf. Bring the broth to a gentle simmer. Return the seared chicken breasts to the pot. Cover and simmer for 15-20 minutes, or until chicken is cooked through and easily shredded.

Remove the chicken from the pot and place it on a cutting board. Shred the chicken using two forks, then set aside. Discard the bay leaf from the pot.

Add the orzo pasta to the simmering broth. Cook for 8-10 minutes, or according to package directions, until the orzo is al dente. Stir occasionally to prevent sticking.

Stir the shredded chicken back into the soup. Add the fresh lemon juice, lemon zest, chopped dill, and chopped parsley. Stir well to combine. Taste and adjust seasoning with salt and black pepper as needed.

Ladle the hot soup into bowls and serve immediately. Garnish with an extra sprinkle of fresh herbs or a lemon slice if desired.