In food processor or blender, process 1 pound of strawberries with stems and hulls removed until pureed. Transfer to a small saucepan and heat the strawberry puree over medium heat. Cook for 15-20 minutes, stirring frequently, until reduced by about 1/2. Cool completely in the fridge before proceeding.
1/2 cup reduced strawberry puree
Preheat oven to 350°F. Line a muffin pan with cupcake liners and set aside.
In a large bowl, whisk together the reduced strawberry puree, sugar, melted butter, oil, buttermilk, eggs, and vanilla until combined.
3/4 cup granulated sugar, 1/4 cup salted butter, 1/4 cup vegetable oil, 1/4 cup buttermilk, 2 large eggs, 1 teaspoon pure vanilla extract
Add the flour, baking powder, baking soda, and salt, stirring just until combined. Stir in finely diced strawberries.
1 1/2 cups cake flour, 1 teaspoon baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon salt, 3/4 cup diced strawberries
Divide the batter between 12-14 cupcake liners, filling only 2/3 full. Bake for 19-22 minutes or until the tops bounce back at a touch or a toothpick inserted into the center of the cupcakes comes out clean. Cool completely before frosting.
To make the frosting, beat the butter until light and creamy. Add the powdered sugar and beat again. Add the reduced strawberry puree and vanilla, mixing again until combined. Transfer to a piping bag fitted with a decorative tip and use to decorate the cooled cupcakes. Garnish with a half a sliced strawberry, if desired.
1 cup salted butter, 1 teaspoon pure vanilla extract, 2-3 Tablespoons reduced strawberry puree, 3-4 cups powdered sugar