Place the whole chicken or chicken parts into a large stockpot and cover with cold water, ensuring the water level is about an inch above the chicken.
Add a few sprigs of thyme and some chopped onion, then bring everything to a gentle simmer over medium heat.
Skim off any foam that rises to the surface to keep the broth clear, and lower the heat to maintain a gentle simmer.
Cook the chicken slowly for about 1.5 hours, until the meat is tender and falling apart, filling your kitchen with a rich, smoky aroma.
Remove the chicken from the pot and set aside to cool slightly, then strain the broth through a fine-mesh strainer into another pot, discarding solids.
While the broth cools a bit, shred the chicken meat into bite-sized pieces, discarding skin and bones.
Return the strained broth to a clean pot and bring it to a gentle simmer over medium heat.
Add sliced carrots, celery, and minced garlic to the simmering broth, cooking for about 15 minutes until the vegetables are vibrant and just tender.
Stir in the shredded chicken, then add lemon zest and a squeeze of lemon juice to brighten the flavors.
Season the soup with salt and pepper to taste, then sprinkle with chopped parsley and additional herbs just before serving.
Ladle the hot, smoky chicken soup into bowls, and enjoy the comforting aroma and tender, flavorful ingredients with a slice of crusty bread if desired.
