Prep: Preheat the oven to 350°F.
Flour mixture: In a small bowl, stir together cake flour and baking powder. Set aside.
Separate the eggs: Separate the egg whites and egg yolks into two separate large mixing bowls. Be careful not to get any yolks into the egg whites. Set the yolks aside.
Egg white mixture: To the egg whites, add cream of tartar. Use an electric hand mixer to beat the mixture on low-medium speed until it becomes very frothy like cappuccino foam.
Beat to stiff peaks: Slowly sprinkle in 100g of granulated sugar, one spoonful at a time, mixing thoroughly in between each addition. Once all the sugar has been added, continue beating on medium speed until it becomes stiff peaks. Set aside.
Egg yolk mixture: To the egg yolks, add the remaining 50g of sugar and mix briefly with the same hand mixer. Add the orange zest, orange juice, oil, and vanilla extract. Mix until combined.
Sift in flour mixture: Use a fine mesh sieve to sift the flour mixture into the egg yolk mixture. Mix on low speed until combined and smooth.
Fold together: Add about ⅓ of the egg white meringue into the egg yolk mixture. Use a spatula to fold together until mostly combined. Add the rest of the meringue and fold together until no streaks remain and you have a fluffy batter.
Fill pan: Pour the batter into a 10" tube pan (do not grease or line the pan!). Lift and drop the pan on the counter to knock out any large air bubbles.
Bake: Bake for about 35-40 minutes or until the top is golden brown. After taking it out of the oven, immediately flip the pan upside down and let it cool completely this way. Ensure there's airflow underneath the pan, either by resting the pan on its feet (most tube pans have these) or on a wire rack.
Release from pan: Once cooled, flip the pan back over and run an offset spatula or skewer around the edges of the cake. Grasp the middle column of the pan and lift the cake out of the pan. Run the offset spatula underneath the cake to release it from the bottom plate. Flip the cake onto a serving plate.