Heat a large heavy-bottomed pot over medium heat and add the olive oil, allowing it to warm up until shimmering.
Add the diced onion to the pot and sauté until translucent and fragrant, about 5 minutes. You should hear a gentle sizzle and see the onions turn a light golden color.
Stir in the minced garlic and cook for another 30 seconds until fragrant, taking care not to burn it.
Place the thinly sliced chicken into the pot and cook for about 5-7 minutes, stirring occasionally, until the chicken pieces are lightly browned and cooked through.
Pour in the chicken broth and bring the mixture to a gentle simmer. Let it cook for about 10 minutes, allowing the flavors to meld and the broth to develop a clear, inviting appearance.
While the soup simmers, zest the lemon using a microplane or fine grater, being careful to only peel the bright yellow outer layer.
Juice the lemon and add the fresh lemon juice to the soup, stirring well to incorporate the citrus brightness.
Stir in the lemon zest, chopped parsley, and thyme, then let the soup simmer for another 5 minutes to infuse the herbal and citrus flavors.
Taste the soup and season with salt and freshly ground pepper as needed. Adjust the seasoning to your preference.
Remove the soup from heat and let it rest for a couple of minutes to allow flavors to settle and the broth to clarify slightly.
Serve the bright lemon chicken soup hot, garnished with additional chopped herbs if desired, and enjoy its lively, comforting flavor.
