Preheat the oven to 325F if using a fan-assisted oven. If not, preheat to 350F.
Line three 12-hole muffin pans with paper liners.
Using the whisk attachment of your electric mixer, beat the eggs and sugar together until they reach ribbon stage. Start at the lowest speed then gradually turn up the speed until you reach the highest setting. The process takes anywhere from five to 10 minutes depending on the room temperature. "Ribbon stage" means that when the whisk attachment is lifted, the egg mixture falls down into the bowl like a ribbon.
Sift the cake flour directly into the egg-sugar mixture. Fold by hand using a spatula until evenly blended.
Add the oil and fold in until no streaks are visible.
Gently stir in the lemon zest.
Scoop the cake batter into the prepared pans. Fill to ¾ capacity.
Bake the cakes for 15 to 16 minutes or until lightly browned at the top and springy when touched.
Remove the cakes from the pans and cool on a rack.