The earthy flavor of the lentils is set off by the tartness of the tomatoes and a spoonful of wine vinegar, which is stirred in just before serving the soup.

1 1/2 tablespoons olive oil

3 carrots, chopped

2 stalks celery, sliced

1 onion, chopped

Salt and pepper

2 cloves garlic, minced

1/4 teaspoon dried thyme

1 dried bay leaf

1 can (28 ounces) whole tomatoes, with their juice

4 cups water

1 cup lentils, picked over and rinsed well

1 tablespoon wine vinegar

In a large pot or Dutch oven, heat oil over medium heat. Add carrots, celery, onion, 1 teaspoon salt, and 1/4 teaspoon pepper. Cook until onion is translucent, about 5 minutes. Add garlic, thyme, and bay leaf, and cook until vegetables begin to soften, 2 to 3 minutes longer.
Add tomatoes with their liquid, breaking them up with a large spoon. Add water and lentils, and bring to a boil. Reduce heat, and simmer, partially covered, until lentils are tender, about 30 minutes. Just before serving, stir in vinegar.