Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan or loaf pan, then line with parchment paper, leaving overhang for easy removal.
In a medium bowl, whisk together flour, baking powder, and salt.
In a large bowl, rub the sugar and citrus zest together with your fingertips until fragrant and slightly moist.
Add eggs to the sugar mixture one at a time, whisking well after each addition until the mixture becomes pale and slightly thickened. Stir in yogurt, oil, and vanilla extract until smooth and well combined.
Gently fold the dry ingredients into the wet mixture using a spatula, mixing just until no dry spots remain.
Pour the batter into your prepared pan and smooth the top. Bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean with just a few moist crumbs.
Let the cake cool in the pan for 10 minutes before transferring to a wire rack.
If using the optional glaze, whisk together citrus juice and powdered sugar, then brush over the warm cake, allowing it to soak in.