Simmer the garlic in the broth and water for 4 to 5 minutes. Add the potatoes, cover and simmer for 10 minutes or until tender. Add the chicken, lemon zest and simmer gently, without boiling, for 5 minutes or until cooked through. Remove the broth from the heat and add the cilantro and lemon juice.
Sprinkle each portion with Parmesan and serve immediately.