My Creamy Chicken and Vegetable Soup is one of my favorites. It keeps in the refrigerator for a few days and you can easily pack some in an insulated thermos for a hot lunch.
Melt butter in a large pot. Add carrots, leek, celery, and garlic. Stir. Cover pot and reduce heat to low. Cook for 30 minutes.
Add stock, chicken, tomatoes, and remaining 1 teaspoon salt. Bring to a simmer and cook until chicken is cooked through, about 10 minutes.