Prepare Chicken - Generously season both sides of the chicken breasts with salt and pepper
Sear the Chicken - In a large pot or dutch oven, heat 1 tablespoon of olive oil over medium heat. Once hot, add the chicken, sear until the surface lightly browns, 3 to 4 minutes. Flip and cook for another 3 minutes. Transfer chicken to a plate.
Saute Aromatics - Add 1 tablespoon olive oil to the pot. Once hot, add the onion, celery, and carrots. Saute and cook for about 3 minutes, or until the vegetables are lightly browned. Add the garlic, Italian seasoning, salt, and pepper. Saute for 30 seconds, until fragrant. Add the tomato paste, stir and cook for 1 minute.
Simmer the Soup - Add the diced tomatoes, potatoes, chicken, and chicken stock to the pot. Bring the stock to a boil, cover the pot and reduce to a simmer over low heat. After 10 minutes, flip the chicken over and adjust heat as needed. Cover and cook until the internal temperature reaches 160 to 165ºF (71 to 74ºC), about 5 to 10 minutes.
Shred the Chicken - Turn off the heat and remove the chicken from the pot. Once the chicken is cool enough to handle, shred into smaller pieces, then set aside.
Cook Vegetables - Add the zucchini, green beans, mushrooms, and corn. Bring the stock to a simmer over medium heat, stir and cook, 4 to 5 minutes, or until the zucchini is tender.
Warm the Chicken - Add the shredded chicken back to the soup, stir to combine. Simmer for 3 to 5 minutes, or until chicken is warm and potatoes are tender. Season with salt and pepper to taste.
To Serve - Serve the soup hot, garnished with chopped parsley.
Notes
Recipe Yield: 12 cups
Serving Size: 1 cup
Using Pre-Cooked Chicken: 3 cups of pre-cooked shredded chicken or rotisserie chicken can be substituted for the chicken breasts. Skip adding the chicken to the simmering step and cook the soup until the potatoes are tender. Simmer the remaining vegetables, then add in the shredded chicken until warmed through.
For a Thinner Soup: Add 1 to 2 cups of chicken stock at the end of cooking.
Storing and Reheating: Cool the soup thoroughly. Store in an airtight container in the refrigerator for up to 5 days. Reheat on the stovetop over medium heat until hot. Add more chicken stock if needed to thin out the soup.
Freezing: Cool the soup to room temperature and then store in resealable plastic bags for up to 1 month. Defrost the soup, then reheat.