Tomato lentil soup combines tomatoes with lentils, bean-like legumes, to form a hearty soup. An adaptable dish, tomato lentil soup has a wide variety of ingredient choices and can, therefore, be spicy or mild and contain many or few other vegetables and seasonings. It is often served with a crusty, rustic bread.
The only necessary ingredients in tomato lentil soup are tomatoes or tomato paste; dried lentils; and a liquid base such as water, vegetable stock, or chicken stock. Additional vegetables and seasonings are normally included, however. Onions, carrots, and celery are usually added, and spinach, chickpeas, potatoes, and bell peppers are also choices. Seasonings include herbs, like garlic, rosemary, and bay leaves, and a wide variety of spices. Dill, oregano, cumin, and cloves, as well as salt and pepper, are just some of the spices that can be added to this dish.
In addition to vegetables and seasonings, diced bacon or pancetta, a type of high-quality Italian bacon, may be included in tomato lentil soup. Balsamic or a red wine vinegar is also a frequent addition. Dry red wine may be added as well for a still more complex taste. Occasionally, butter can be include to give a slightly creamy texture.
Further variation comes from the title ingredients. Tomatoes may be canned or fresh, but are usually diced. They can first be fire-roasted or left completely uncooked. Roma tomatoes may be used instead of larger versions and pureed rather than diced before being added to the soup. Alternately, tomato paste or a combination of paste and tomato pieces can be used. Lentils may be brown, red, or green.
There are fewer variations in the way different versions of tomato lentil soup are made. In most versions, the onions are either first sauteed in oil, or if bacon is used, the meat is fried first and the onions are sauteed in the remaining fat. Celery and carrots, if used, are normally sauteed with the onions, and some versions will include the garlic at this stage as well. Then most or all of the other ingredients are added. Lentils may be soaked first or boiled with stock and tomatoes before the seasonings are added, but they are usually cooked with the other ingredients without being soaked.
The soup is normally brought to a boil and then allowed to simmer until the lentils are soft. Afterward, salt and pepper are added to taste. Tomato lentil soup may be served without garnish, the most common of which are basil sprigs, sour cream, or feta cheese.