Step 1: Prepare the Lemon Cupcake Batter

1. Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.
2. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
3. In a large mixing bowl, cream the butter and sugar using an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
4. Beat in the eggs, one at a time, ensuring each is fully incorporated. Add the lemon juice and zest, mixing until combined.
5. Gradually add the dry ingredients in three additions, alternating with the buttermilk. Begin and end with the dry ingredients, mixing just until combined—avoid overmixing to ensure tender cupcakes.
6. Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Step 2: Bake the Cupcakes

1. Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
2. Remove from the oven and allow the cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

Step 3: Make the Strawberry Buttercream Frosting

1. While the cupcakes are cooling, prepare the frosting. In a large bowl, beat the butter with an electric mixer on medium speed until creamy and smooth.
2. Gradually add the powdered sugar, one cup at a time, mixing well after each addition.
3. Add the strawberry puree, vanilla extract, and a pinch of salt, and mix until combined. Adjust the consistency by adding heavy cream or milk if needed. The frosting should be thick yet spreadable.

Step 4: Frost and Decorate

1. Once the cupcakes are completely cool, use a piping bag with a star tip or an offset spatula to frost each cupcake with the strawberry buttercream.
2. Garnish with fresh strawberry slices, lemon zest, or any decorative element of your choice.