This lentil-sweet potato soup is an all-weather, all-season Mediterranean diet and Greek diet adaptation of the many traditional lentil soups recipes around Greece. Indeed, both lentils, an Old-World Mediterranean diet ingredient and one of the earliest cultivated native legumes in the Eastern Mediterranean, and sweet potatoes, a New-World tuber, have long been important Ikaria longevity foods, which, as you know by now, is a Blue Zone, the term coined by Dan Buettner to refer to the places around the world where people live a very long time. Iron-rich spinach and antioxidant-rich tomatoes add even more gorgeous color to this uber healthy, really easy Greek lentil soup recipe! You can enjoy it at room temperature, too!