Pour the chicken stock into a heavy-bottomed pot and bring it to a gentle simmer over medium heat, until it’s steaming and fragrant.
Add chopped carrots, celery, and diced onion to the simmering broth. Stir gently with a wooden spoon and cook for about 10 minutes until the vegetables are tender but still hold their shape, and the broth begins to develop a richer aroma.
Stir in your leftover cooked chicken pieces, allowing them to warm through as the flavors meld together for another 15-20 minutes.
Taste the broth and season with salt and pepper as needed. Squeeze in fresh lemon juice to brighten the flavors and stir well.
Sprinkle chopped fresh parsley over the soup, and drizzle a splash of olive oil for added richness. Give everything a gentle stir to combine.
Let the soup rest for a few minutes to allow the flavors to settle and the temperature to even out.
Serve the healing chicken soup hot, garnished with extra parsley and a lemon wedge if desired. Enjoy its comforting aroma and soothing texture.