Heat the oven and prepare the pan: Preheat your oven to 180°C (350°F).Grease with butter or spray with non-stick spray the base and sides of a 25x38cm (10×15-inch) baking pan /swiss roll pan/jelly roll pan. Line the pan with parchment paper, ensuring the paper overhangs the pan's sides. This will help you later when trying to remove the sponge from the tin. Grease the parchment paper with butter, as this will help with peeling the paper off once the sponge has baked.
Whip the eggs and sugar: In the bowl of a stand mixer fitted with the whisk attachment, add the eggs, sugar, vanilla extract and lemon zest and whip until the mixture is light and creamy, about 5 minutes. When lifting out the whisk, you want to be able to see trails of the mixture for a few seconds. Add the oil and whisk until incorporated.
Sift dry ingredients: Into a separate bowl, sift in the flour, baking powder and salt. Sift ¼ of the flour mixture into the whisked eggs and, using a metal spoon or rubber spatula, gently fold through until just combined. Fold together: Sift in the remaining flour mixture and again fold through whilst rotating the bowl. Ensure that you scrape right to the bottom of the bowl where flour air-pockets can remain. Try not to over mix/fold, as this will deflate the lovely air created during the initial whisking of the eggs.
Pour into the prepared pan: Pour the batter into the prepared pan and shake/wiggle the pan to help guide the batter into the pan’s corners. If necessary use an offset spatula if necessary to help smooth out the batter.
Bake: Bake in the oven for 8-10 minutes until a toothpick inserted into the centre comes out clean and springs back when pressed lightly.
Prepare your teatowel: Whilst the sponge is baking, lay a tea towel or piece of parchment paper on your work surface and dust lightly with powdered icing sugar. (Alternatively, sprinkle with caster sugar)
Invert sponge onto the teatowel: Once the sponge has baked, remove it from the oven and immediately invert the sponge onto the tea towel whilst it is still hot.
Peel off paper and roll: Gently peel off the parchment paper on the bottom of the sponge. Starting from the sponge’s short end, using your hands, roll the sponge up gently but firmly until it is totally rolled into the tea towel (or parchment paper). Set the roll aside with its seam side down to cool completely.