I've had challah before, both store-bought and home baked. It's one of our favorite sweet breads and I always serve it on Christmas morning and Christmas lunch too. I didn't think it will taste any better using sourdough starter and then I saw the beautiful photos of sourdough challah, adapted the recipe adding a large steamed and mashed sweet potato. I love the slightly tangy flavor and the soft tight crumb that reminds me of sponge cake.