Lentil Vegetable Soup

Name: Lentil Vegetable Soup
Ingredients: 2 ½ tablespoons extra-virgin olive oil; 1 onion, chopped (¾ cup); 2 carrots, peeled and chopped (¾ cup); 2 celery stalks, peeled and chopped (⅔ cup); 3 garlic cloves, minced (1 tablespoon); 1 tablespoon coarse salt; 1 small tomato, chopped (⅓ cup); 1 tablespoon tomato paste; 2 cups brown or green lentils; ½ teaspoon dried thyme; 1 small bay leaf; ¼ teaspoon freshly ground black pepper; 6 cups chicken broth or vegetable broth; 4 cups water, plus more if needed; 2 teaspoons red wine vinegar; Garlic Croutons , optional