Gather all your ingredients, then preheat your large pot over medium heat.
Add olive oil to the pot and sauté chopped onions and minced garlic until fragrant and translucent, about 3-4 minutes. The onions should be soft and slightly golden, filling your kitchen with a savory aroma.
Stir in diced chicken breast and cook until it starts to brown lightly, about 5-6 minutes, stirring occasionally to prevent sticking. The chicken will turn opaque and firm up, releasing a mild aroma.
Pour in the chicken broth, then increase the heat to bring the mixture to a gentle boil. Once bubbling, reduce the heat to low and let it simmer uncovered for about 20 minutes, allowing the flavors to deepen and the chicken to become tender.
Add sliced carrots and celery to the pot. Continue simmering for another 10 minutes until the vegetables are tender and the broth is flavorful.
Season the soup with salt and pepper to taste. Finish by stirring in a splash of lemon juice or vinegar to brighten the flavors, then sprinkle with chopped fresh herbs for a vibrant finish.
Use a ladle to serve the hot, hearty soup into bowls. Garnish with extra herbs if desired and enjoy this comforting, protein-rich meal that’s perfect after a long day or for a quick lunch.