Preheat the oven to 350F degrees and line a muffin pan with muffin papers.
In a medium bowl whisk together the flour, baking powder and salt.
In a large bowl using an electric mixer, beat the butter, sugar and lemon zest until fluffy (about 2-3 minutes).
Beat in the eggs 1 at a time and vanilla extract.
In a liquid measuring cup whisk together the sour cream, milk and lemon juice.
Beat about ⅓ of the flour mixture into the butter mixture, followed by about ⅓ of the sour cream mixture. Turn off the mixer and scrape down the sides of the bowl as necessary. Repeat the process until all the flour and all the sour cream mixture is incorporated.
Spoon the batter into the prepared muffin pan, filling each liner about ¾ full. You should end up with about 12-14 cupcakes total.
Bake on the middle rack of your oven for 16-19 minutes, or until an inserted toothpick comes out clean.