Lentil Vegetable Soup

INGREDIENTS

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