Preheat the oven to 350°F, then grease a 9 x 5-inch pan with nonstick spray and line it with parchment paper.
Mix the flour, baking powder, salt, and baking soda together in a medium mixing bowl.
In the bowl of your mixer, beat together the granulated sugar and lemon zest. Mix in the sour cream, vegetable oil, eggs, lemon juice, and vanilla extract. Slowly add the flour mixture, stirring until just combined.
Pour the batter into the prepared pan.
Bake for 45-50 minutes, or until a toothpick inserted into the center of the loaf comes out clean. Allow the lemon loaf to cool completely.