Preheat the oven to 350F (180C) degrees and set the oven rack to the middle.
Grease and flour a 10-inch bundt pan, making sure to get into all the creases.
In a medium bowl whisk together the flour, baking powder, baking soda and salt.
In a liquid measuring cup, whisk together the sour cream, buttermilk and lemon juice. (If there are a few lumps - don't worry).
In a very large bowl using an electric mixer beat the butter, sugar and lemon zest until fluffy.
Add in the vanilla extract, then mix in the eggs 1 at a time.
With the mixer on low speed, beat in about 1/3 of the flour mixture followed by about 1/3 of the buttermilk. Turn off the mixer and scrape down the sides of the bowl.
Repeat the process until all of the dry ingredients and buttermilk mixture are incorporated.
Spoon the batter into the prepared bundt pan and smooth the top.
Bake in the preheated oven for 50-60 minutes, or until an inserted toothpick comes out clean
Remove the pan from the oven and cool for 30 minutes in the pan. Then carefully insert to remove the cake.