Trim the chicken breasts and remove any unwanted fat. Cut them into small, even pieces. Smaller pieces cook quickly and make the soup easier to portion for meal prep.

Wash the vegetables well before cutting them. Dice the onion and zucchini, then slice the celery. Chop the cauliflower and spinach into manageable pieces for even cooking.

Heat olive oil in a large soup pot over medium heat. Add the diced onion and cook for three minutes. Stir occasionally until the onion becomes soft and slightly golden.

Add the minced garlic to the softened onion. Stir for about thirty seconds. Be careful not to burn the garlic because it can become bitter and overpower the soup.

Add the chicken pieces to the pot. Stir them with the onion and garlic. Cook for about five minutes until the chicken begins turning white on the outside.

Add the zucchini, celery, cauliflower, and diced tomatoes. Stir everything together so the vegetables become coated with the flavorful onion mixture.

Pour the chicken broth into the pot. Add oregano, thyme, smoked paprika, black pepper, and salt. Stir well and bring the soup to a gentle boil.

Reduce the heat to medium-low after the soup begins boiling. Cover the pot partially and simmer for about 15 minutes. Stir occasionally until the chicken and vegetables are fully cooked.

Add the chopped spinach during the final few minutes. Stir until it wilts into the hot broth. Adding spinach later helps preserve its fresh color and delicate texture.

Turn off the heat and stir in fresh lemon juice and parsley. Taste carefully and adjust the seasoning if needed. Ladle the hot soup into bowls and serve immediately.