Here's a bread tidbit from head miller/baker Steve Horton:
"For our brioche bread, we use a sweet liquid levain, a naturally yeasted culture. It provides leavening and flavor. The result? A brioche is a light-textured loaf that balances sweetness and tang in flavor. Use it as toast -- for a unique grilled cheese with a savory filling or just warm with a touch of jam."
Try it for yourself, find the store nearest you!