Vegetarian lentil soup is low in fat but high in fiber, protein, and flavor, and, cooking with lentils is a great way to stretch your food budget since they are so filling and so cheap (and lentils are great to shop for in bulk, too). All of this combines to make this homemade lentil soup recipe one of the most perfect meals to make at home if your family is on a budget, whether you're vegetarian, vegan or not. This simple vegetarian and vegan lentil soup recipe calls for lots of healthy vegetables, including potatoes, carrots, celery, and spinach, so it really is a balanced vegetarian meal in itself. Add a quick side green salad and maybe some homemade dinner rolls, and you've got yourself a complete meal. This recipe is vegetarian, vegan, and gluten-free (though you'll need to be sure to use a gluten-free vegetable broth, so check the label or make your own so you know what's in it, or make your own homemade vegetable broth).