Begin by making the crumb topping in a small bowl by mixing the melted butter, flour and sugar together until it becomes course crumbs...set aside
Preheat the oven to 350 degrees. Line a 12 count muffin tin with paper liners or grease generously to prevent sticking.
Whisk together the butter, eggs, sourdough starter, sour cream, and vanilla until smooth.
Add the remaing dry ingredients and strawberries with your wet mixture. Be sure to not over mix the batter so the muffins will stay tender.
Divide the batter evenly into 12 muffins and sprinkle the tops with the crumb topping. Make sure to press the crumble gently on the top of the batter.
Bake for 20 to 25 minutes or until a toothpick inserted into the center of a muffin comes out clean. Remove to a cooling rack
These will be good covered at room temperature for 3 days or freezing them for up to 3 months works wonderfully.