You have the option to use either store-bought or homemade sourdough starter for these muffins. Store-bought starters are convenient and time-saving, while making your own gives you more control over fermentation and flavor. If you prefer to make your own starter, a helpful approach is to ask a friend who has an active starter if they can provide you with some of their discard. By feeding it, you can maintain and have a steady supply of starter available for various recipes.