Combine flour, baking powder, baking soda, and salt in a medium bowl and set aside.
In a large bowl, beat the egg and yolk and sugar until thickened and lightened to a cream color, about 2 minutes.
Add the oil and vanilla and mix on low speed until blended.
Mix in the sour cream just until no streaks remain, then the flour mixture. Mix until the batter is smooth.
Pour into 24 regular size muffin tins, lined with cupcake liners.
Bake at 350°F for about 23 minutes, until toothpick inserted in center comes out clean.
Remove from oven; cool on a wire rack 10 minutes, then remove cupcakes from pan and cool completely.