Heat a large heavy-bottomed pot over medium heat and add olive oil. Once shimmering and fragrant, add diced onion. Sauté until translucent and soft, about 5 minutes, until it smells sweet and looks glossy.
Add minced garlic to the pot and cook for another minute, stirring constantly, until fragrant and slightly golden at the edges.
Place thinly sliced chicken into the pot, spreading it out evenly. Cook for about 5-7 minutes, stirring occasionally, until the chicken is lightly browned and cooked through.
Pour in the chicken broth and bring the mixture to a gentle simmer. Reduce the heat to low and cook for 10 minutes, allowing the flavors to meld and the chicken to stay tender.
While the soup simmers, zest the lemon using a microplane, collecting the fragrant citrus peel. Then, juice the lemon to extract about 2 tablespoons of fresh lemon juice.
Add lemon zest, lemon juice, chopped parsley, and thyme to the soup. Stir well and let it simmer uncovered for another 5 minutes, brightening the broth and releasing fresh herbal aromas.
Taste the soup and adjust seasoning with salt and pepper, adding more lemon juice if you want extra brightness.
Remove the soup from heat and let it rest for a couple of minutes, allowing flavors to settle and the broth to clarify slightly.
Ladle the bright, citrus-infused chicken soup into bowls, ensuring each serving has tender chicken slices, aromatic herbs, and a clear, flavorful broth. Serve hot.
