Preheat your oven to 350°F (175°C).
Grease and flour a round cake pan.
In a mixing bowl, combine yogurt, sugar, and eggs.
Whisk until well blended.
Add in vegetable oil and vanilla extract; mix well.
In another bowl, whisk together flour, baking powder, and salt.
Gradually add dry ingredients to the wet mixture.
If using, fold in lemon zest for added flavor.
Pour the batter into the prepared cake pan.
Bake for 30-35 minutes, or until a toothpick comes out clean.