Gluten, Dairy, Soy, Nut and Egg-Free
Add the olive oil to the bottom of a large stock pot and heat it over medium-high. Add the onion, carrots and celery to the pan and sauté for 5 minutes, or until the vegetables soften. Add the zucchini and continue cooking for another 3 minutes. Add the string beans, tomatoes, chicken stock, thyme and parsley. Bring the soup to a boil, then reduce the heat to a simmer and cook for about 20 minutes.
While the soup is simmering, make the pesto. Add the basil leaves, olive oil, tomato paste and garlic to the bowl of a food processor and process until smooth. Set aside.
When the soup is done and the vegetables are tender, add the peas if you are using them. Stir in the pesto, remove the thyme and parsley sprigs and serve piping hot.