01 - Preheat oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper cupcake liners.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed.
03 - In a large mixing bowl, beat the softened butter and granulated sugar together using an electric mixer on medium speed until pale, light, and fluffy, approximately 3 minutes.
04 - Add the eggs one at a time, beating well after each addition until fully incorporated before adding the next.
05 - Mix in the fresh lemon juice and finely grated lemon zest until evenly combined.
06 - Add the dry ingredient mixture to the wet ingredients in three additions, alternating with the whole milk in two additions, beginning and ending with the dry ingredients. Mix until just combined; do not overmix.
07 - Gently fold the diced fresh strawberries into the batter using a spatula, taking care not to overmix and deflate the batter.
08 - Divide the batter evenly among the prepared cupcake liners, filling each liner approximately two-thirds full.
09 - Bake on the center rack for 16 to 18 minutes, or until a toothpick inserted into the center of a cupcake comes out clean and the tops spring back lightly when touched.
10 - Remove the cupcakes from the muffin tin and transfer to a wire cooling rack. Allow to cool completely before frosting, approximately 30 minutes.
11 - Beat the softened butter in a mixing bowl until smooth and creamy. Gradually add the sifted powdered sugar, beating on low speed until incorporated, then increase to medium speed. Add the fresh lemon juice, strawberry puree, vanilla extract, and salt. Beat until light, fluffy, and well combined.
12 - Once the cupcakes are completely cool, frost generously with the strawberry lemonade buttercream using a piping bag or spatula. Optionally garnish with thin strawberry slices or additional lemon zest.