1. Preheat oven to 375°F (190°C) and line a 12-cup muffin tin with liners.

2. In a bowl whisk together flour, baking powder, salt, and sugar.

3. In a separate bowl whisk melted butter, eggs, milk, vanilla extract, and sourdough starter until smooth.

4. Gently fold wet ingredients into dry until just combined, being careful not to overmix.

5. Fold diced strawberries into the batter until evenly distributed.

6. In a small bowl combine cold butter, sugar, and flour for streusel topping until coarse crumbs form.

7. Divide batter evenly among muffin cups, filling each three-quarters full.

8. Sprinkle streusel topping over each muffin, pressing lightly to adhere.

9. Bake 22–26 minutes until golden and a toothpick comes out clean.

10. Cool muffins in pan 5 minutes, then transfer to a wire rack.

11. Serve warm with butter or honey alongside coffee or tea.

12. Store cooled muffins in an airtight container at room temperature for up to 2 days or freeze up to 3 months.