Make the Cupcakes
Preheat oven to 350°F (176°C) and line a cupcake pan with cupcake liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a large mixing bowl, whisk together the melted butter, sugar, and vanilla extract until combined.
Add the eggs and whisk until smooth.
Mix in the sour cream until fully incorporated.
Add the milk and whisk until combined.
Gradually add the dry ingredients and mix just until combined. Do not overmix.
Gently fold in the chopped strawberries.
Fill cupcake liners slightly more than halfway full.
Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean.
Remove from the oven and allow the cupcakes to cool completely on a wire rack.
Make the Strawberry Reduction
Place the strawberries in a blender or food processor and puree until smooth. You should have approximately 3/4 cup puree.
Pour the puree into a small saucepan and cook over medium heat.
Bring to a gentle simmer, stirring frequently, until reduced to about 6 tablespoons and noticeably thicker, about 10–15 minutes.
Transfer to a measuring cup and cool completely before using.
Make the Strawberry Buttercream
Beat the room-temperature butter in a large mixing bowl until smooth and creamy.
Add about half of the powdered sugar and mix until combined.
Add 4 tablespoons of the cooled strawberry reduction, vanilla extract, and salt. Mix until smooth.
Add the remaining powdered sugar and beat until light and fluffy.
Add additional strawberry reduction, if desired, until the frosting reaches your preferred flavor and consistency.
Assemble
Pipe the buttercream onto the cooled cupcakes using a piping bag fitted with a large star tip (such as Ateco 844).
Garnish with fresh strawberry halves or slices.
Serve and enjoy.