Panera Black Bean Soup

1 cup chopped white onion
1/2 cup chopped celery
1/2 cup chopped carrot
2 tablespoons vegetable oil
1/2 cup chopped red bell pepper
2 teaspoons minced garlic
1 32-ounce carton vegetable stock
2 15 ounce cans of black beans or 3 to 4 cups cooked black beans
1 to 2 teaspoons salt
1 to 2 teaspoons cumin
1 1/2 tablespoons lemon juice
1 tablespoon cornstarch mixed with 1 tablespoon of water

In a large pot add 2 tablespoons of vegetable oil. Saute onions, celery, and carrots. Sprinkle the vegetables with a pinch of salt to help them release the water in the vegetables. When the onions begin to become translucent add bell pepper and garlic. Continue to saute vegetables until the garlic becomes fragrant. If using canned black beans rinse to remove excess starch. Add beans and vegetable stock to pot. Add 1 teaspoon of salt and the cumin to the soup. Allow the soup to simmer for about 10 minutes to heat through. Taste soup, and adjust salt if needed. Add cornstarch and water mixture to the soup. It will help thicken the soup.