Preheat the oven to 350°F (175°C) and line a 12-cup muffin tin with liners.

In a medium bowl, whisk together the flour, baking powder, and salt until evenly combined.

In a large bowl, cream 1/2 cup softened butter with 1 cup granulated sugar until light and fluffy, about 2–3 minutes.

Add lemon zest, then beat in the eggs one at a time, followed by vanilla.

Alternate adding the dry ingredients and the milk, beginning and ending with the dry, folding in sour cream and finally the lemon juice until the batter is smooth.

Spoon batter into liners about two-thirds full.

Bake for 16–20 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Cool the cupcakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Hull and quarter 8 ounces of strawberries.

Puree them in a blender or food processor until smooth.

If the puree is watery, simmer gently in a small saucepan for 3–4 minutes to concentrate flavor, then cool completely before adding to frosting.

In a large bowl, beat 3/4 cup slightly firm butter until creamy.

Gradually add 3 cups powdered sugar, alternating with tablespoons of the cooled strawberry puree, until you reach your preferred sweetness and color.

If the frosting is too soft, add more powdered sugar; if too stiff, add up to 1 tablespoon of whipping cream.

Beat until light and smooth.

Once cupcakes are cool, use an offset spatula or piping bag to top each cupcake with a generous swirl of strawberry buttercream.

Garnish with a small slice of fresh strawberry or a curl of lemon zest for contrast.

Serve at room temperature.