Place the chicken in a large pot and cover with chicken broth. Bring to a gentle boil over medium heat, then reduce heat to low and simmer for 20-25 minutes until cooked through.
While the chicken cooks, dice the onion and mince the garlic, preparing to sauté.
Remove the cooked chicken from the broth, shred it with two forks, and set aside.
In the same pot, heat olive oil over medium heat. Add diced onion and sauté until translucent and fragrant, about 5 minutes, until it starts to look glossy and soft.
Add the minced garlic to the pot and cook for another minute until fragrant, listening for a gentle sizzle.
Return the shredded chicken to the pot, pouring in the remaining broth to reheat and meld flavors. Bring to a gentle simmer.
Add chopped zucchini and cook for about 10 minutes until tender but still slightly firm, adjusting the heat as needed.
Stir in the chopped spinach and cook for another 2-3 minutes until wilted, watching for a vibrant green color.
Squeeze fresh lemon juice into the soup, then season with salt and pepper to taste. Stir well to combine.
Garnish the soup with chopped herbs for freshness and serve hot, enjoying the warm, hearty flavors and bright citrus notes.
