In a small saucepan, combine strawberry puree and 1 tablespoon sugar over medium heat. Simmer for 15-20 minutes until reduced to approximately 0.33 cup. Allow to cool completely.

Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) and line a 12-cup muffin tin with paper liners.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt.

In a large bowl, cream 0.5 cup butter and 1 cup sugar together until light and fluffy.

Beat in the egg, vanilla extract, and sour cream until well combined.

Gradually add dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Drop 1 teaspoon of the cooled strawberry reduction onto each cupcake and use a toothpick to swirl it into the batter. Reserve remaining reduction for frosting.

Bake for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean. Transfer to a wire rack to cool completely.

For the frosting, beat 1 cup softened butter until creamy. Gradually add powdered sugar, 3 tablespoons of the strawberry reduction, and a pinch of salt.

Beat the frosting on high speed for 2 minutes until light and airy. Pipe onto cooled cupcakes.