Chop the onion, carrots, and celery into small, even pieces and set aside.
Heat olive oil in a large pot over medium heat, then add the chopped onion, carrots, and celery.
Sauté the vegetables for about 5 minutes until fragrant and slightly softened, with aromas filling the kitchen.
Place the chicken breasts into the pot, then pour in water to cover all ingredients.
Bring the mixture to a gentle simmer, then reduce the heat to low and cook for 30-40 minutes, skimming any foam that forms on top.
Remove the chicken breasts from the broth, then shred the meat finely using two forks.
Return the shredded chicken to the pot, add dried thyme and chopped parsley, and stir to combine.
Season the broth with salt and pepper to taste, then cook for another 10 minutes to allow flavors to meld.
Meanwhile, zest the lemon and squeeze out the juice, then add the lemon juice and zest to the soup just before serving.
Taste the soup and adjust seasoning if needed, adding more lemon for brightness or salt for saltiness.
Serve the soup hot in bowls, garnished with additional fresh parsley if desired. Enjoy the fresh, lively flavors in every spoonful!
