Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius). Place paper cupcake liners in a regular size 12 cup pan. 

In a bowl, mix together the flour, baking soda, baking powder and salt. Set aside.

In another bowl, beat the eggs on high speed until they become fluffy and they triple in volume. I highly recommend a stand mixer as this takes about 3-4 minutes. 

Add sugar and continue beating on medium speed.

Add the vanilla extract and lemon zest and beat for another 30 seconds on medium speed

Increase the speed to high and slowly drizzle in the oil. Take your time, if you add the oil too fast the mixture will not hold its volume. 

Add half the dry mixture and mix gently on low speed, only until the dry mixture is incorporated

Add half the buttermilk and lemon juice and continue mixing gently to incorporate

Add the remainder of the flour and mix gently as before

Add the remainder of the buttermilk and lemon juice. 

Use an ice cream scoop or a spoon to fill the liners about 2/3 of the way

Bake in the preheated oven for 18 minutes. 

Check doneness by inserting a wooden toothpick into the center of the cupcake. If the toothpick comes out clean, the cupcakes are done.

Let cupcakes cool in the pan for 3-4 minutes, then move them to a cooling rack. If you leave them in the pan longer, the liners will become soggy. 

Frost cupcakes once they have completely cooled