01 - Preheat oven to 350°F. Line a 12-cup muffin tin with cupcake liners.
02 - In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until evenly distributed.
03 - In a large bowl, beat the softened butter and granulated sugar together until pale, light, and fluffy.
04 - Add the eggs one at a time, beating well after each addition until fully incorporated.
05 - Mix in the fresh lemon juice and grated lemon zest until combined.
06 - Gradually add the dry ingredients to the wet mixture, alternating with the milk. Begin and end with the dry ingredients, mixing until just combined. Do not overmix.
07 - Gently fold the diced fresh strawberries into the batter using a spatula, taking care not to overmix.
08 - Divide the batter evenly among the cupcake liners, filling each approximately two-thirds full.
09 - Bake for 16 to 18 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
10 - Remove the cupcakes from the muffin tin and transfer to a wire rack. Allow to cool completely before frosting.
11 - Beat the softened butter until creamy and smooth. Gradually add the sifted powdered sugar, beating until incorporated. Add the 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 buttercream. Garnish with fresh strawberry slices or additional lemon zest if desired.