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 the mixture becomes pale, light, and fluffy, approximately 3 to 4 minutes.
04 - Add the eggs one at a time, beating well after each addition to ensure full emulsification before adding the next.
05 - Mix in the fresh lemon juice and finely grated lemon zest until evenly combined throughout the batter.
06 - Gradually add the dry ingredient mixture to the wet ingredients, alternating with the whole milk. Begin and end with the dry ingredients, mixing on low speed until just combined. Avoid overmixing.
07 - Gently fold the diced fresh strawberries into the batter using a spatula, taking care not to overwork the mixture and crush the fruit.
08 - Divide the batter evenly among the prepared cupcake liners, filling each liner approximately two-thirds full to allow room for rising.
09 - Bake on the center oven rack for 16 to 18 minutes, or until a wooden toothpick inserted into the center of a cupcake emerges clean. Rotate the pan halfway through baking for even results.
10 - Remove the cupcakes from the muffin tin and transfer to a wire cooling rack. Allow them to cool completely before frosting, approximately 45 minutes to 1 hour.
11 - In a mixing bowl, beat the softened butter on medium speed until smooth and creamy, about 2 minutes. Gradually add the sifted powdered sugar, beating on low speed until incorporated, then increase to medium-high and beat until light and fluffy. Add the fresh lemon juice, strawberry puree, vanilla extract, and a pinch of salt. Continue beating until the frosting is airy, smooth, and fully combined.
12 - Once the cupcakes have cooled completely, frost generously with the strawberry lemonade buttercream using a piping bag or spatula. Optionally garnish with thin strawberry slices or a sprinkle of additional lemon zest.