Preheat your oven to 350F (180C) and position the rack in the middle. Grease and flour a 10-inch bundt pan, ensuring all creases are covered.
In a bowl, whisk together the flour, baking powder, baking soda, and salt.
In a liquid measuring cup, combine the sour cream, buttermilk, and lemon juice (lumps are okay).
In a very large bowl, use an electric mixer to beat the butter, sugar, and lemon zest until fluffy.
Add the vanilla extract, then mix in the eggs one at a time.
With the mixer on low, alternate adding about ⅓ of the flour mixture and ⅓ of the buttermilk mixture. Pause to scrape down the sides of the bowl.
Repeat until all dry ingredients and buttermilk are incorporated.
Spoon the batter into the prepared bundt pan, smoothing the top.
Bake for 50 minutes, or until a toothpick inserted comes out clean.
Let the cake cool in the pan for 30 minutes before carefully removing it.