This hearty and healthy soup is packed with protein and fiber from lentils and a variety of vegetables. Simply sauté chopped onions and garlic in a little bit of olive oil, then add in diced carrots, celery, and potatoes. Add in lentils and vegetable broth and let simmer until lentils are tender. Season with herbs and spices such as thyme and rosemary for a delicious and nutritious meal.