Heat the large soup pot over medium heat, then add the olive oil, allowing it to shimmer and smell fruity.
Dice the chicken breasts into bite-sized pieces, then season with a pinch of salt and pepper.
Add the chicken to the hot oil, cooking until golden and cooked through, about 5 minutes, stirring occasionally.
Stir in the chopped onion and minced garlic, cooking until fragrant and translucent, about 3 minutes, filling the kitchen with a warm aroma.
Pour in the chicken broth and bring to a gentle simmer, skimming off any foam that rises to keep the broth clear.
Stir in the shredded cooked chicken, lemon zest, and a squeeze of fresh lemon juice, then let the soup simmer gently for another 10 minutes to meld the flavors.
Taste the soup and adjust seasoning with more salt, pepper, or lemon juice as needed, until bright and balanced.
Serve the soup hot, garnished with an extra twist of lemon zest or fresh herbs if desired, and enjoy the bright, comforting flavors.