Preheat oven to 425℉
Mix together all dry ingredients in a bowl.
Add rest of ingredients except fruit to bowl, and mix until fully combined.
Let sit for at least 1hr and 30min to get the health benefits of using sourdough.
After fermenting, add fruit of your choice and mix into muffin batter. Chop the fruit up into small pieces if it is larger than the size of a blueberry.
Put into muffin pan and bake for 5-6min at 425℉. Then continue baking for 13-15min at 350℉.
The muffins are done when a toothpick poked into them comes out clean.
Allow the muffins to cool before taking them out of the pan.