Slow Cooker Recipe for Vegetarian Greek Lentil Soup with Tomatoes, Spinach, and Feta

Delicious vegetarian lentil soup with Greek flavors and a sprinkling of Feta! How about an ultra-tasty lentil soup for A Month of Daily Phase One Recipes?  I've been a lover of lentils for quite a few years now so there are many variations of Lentil Soup on my blog, but when I spotted a recipe for Greek Lentils with spinach and Feta in the American Heart Association Healthy Slow Coo