Lentil Soup  1 teaspoon extra-virgin olive oil  1/2 small onion, finely chopped  1 carrot, finely chopped  1 celery stalk, finely chopped  1 garlic clove, minced  Coarse salt and ground pepper  14.5 ounces low-sodium vegetable or chicken broth  3/4 cup cooked lentils (from a 15-ounce can), rinsed and drained  2 teaspoons red-wine vinegar.
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