1. Preheat the oven to 350°F and line a muffin tin with muffin papers.

2. Whisk together the flour, baking powder, and salt in a medium bowl, then set aside.

3. In a large bowl, beat the butter, sugar, and lemon zest until fluffy, about 2-3 minutes.

4. Beat in the whisked eggs.

5. With the mixer on low speed, beat one-third of the flour mixture into the butter mixture.

6. Mix in the sour cream.

7. Scrape down the sides and bottom of the bowl.

8. Beat in another third of the flour mixture, then beat in the milk just until incorporated.

9. Scrape down the bowl again, then beat in the remaining flour mixture.

10. Gently stir in the lemon juice, whisking until smooth if needed.

11. Spoon the batter into the prepared muffin tin, filling each cup about two-thirds to three-quarters full.

12. Bake one muffin tin at a time in the center of the oven for 15-18 minutes, or until a toothpick inserted in the center comes out clean.

13. Cool cupcakes in the pan for at least 10 minutes, then transfer to a wire rack to cool completely.

14. Core the strawberries and puree them in a food processor or blender until smooth.

15. Press the puree through a metal sieve to remove the seeds.

16. Transfer the strained puree to a saucepan over low-medium heat.

17. Gently boil, stirring occasionally, until thick, dark, and jam-like, about 15 minutes.

18. Remove from heat and cool completely.

19. In a large bowl, beat the butter until fluffy.

20. Add 2 cups powdered sugar and beat together, starting on low speed.

21. Add 2-3 tablespoons cooled strawberry puree and beat until combined.

22. Mix in the remaining powdered sugar 1/2 cup at a time, adding 1-2 more tablespoons puree as needed for flavor and consistency.

23. Beat in whipping cream if the frosting is too thick.

24. Frost the cooled cupcakes with a knife or piping bag.