To make the batter: Separate the egg yolks and egg whites. Set aside. (TIP: Cold eggs separate easily. See my note 1 for more details.)
Preheat the oven to 375°F (190°C). Line baker’s half baking sheet with a parchment paper.
In a small bowl, sift together flour and baking powder.
In a mixing bowl with a whisk attachment, whisk the egg yolks, vanilla extract and 1/3 cup of sugar until pale and tripled in size.
In another mixing bowl with whisk attachment, beat the egg whites on medium speed until frothy.
Then add remaining 1/3 cup of sugar, one tablespoon at a time. Increase the speed to medium high and continue to beat until soft peaks form.
Spoon half of whipped egg whites into the egg yolk mixture. Mix with a spatula until smooth, and then add the remaining whipped egg whites. Carefully fold the batter until smooth.
Add sifted flour mixture into the batter and gently fold until no dry flour visible.
In a small bowl, combine oil, milk and lemon zest.
Add ½ cup or so batter into the milk mixture and mix it until smooth.
Pour the mixture into the batter and gently fold it until well combined. (TIP: Fold the batter gently so you don’t deflate the batter.)
Pour the batter into the prepared baking sheet, smooth the surface evenly, with a bench scraper.
Bake the cake for about 15 minutes, or until inserted toothpick comes out clean.
Cool the cake on wire rack for 5-10 minutes. Run a flat spatula or butter knife along the edges and carefully flip the cake out onto a clean surface. Peel off the parchment paper.
Using a sharp serrated knife, cut off the edges. Cut one short side at an angle, as pictured above. It’ll make the roll cake look better after it’s rolled. Cool the cake completely.
To make the whipped cream: In a mixing bowl with a whisk attachment, beat heavy whipping cream, sugar and vanilla extract on medium speed until soft peaks.
To prepare the fruits: Cut the berries and fruits into small pieces.
To assemble the roll cake: Spread the jelly evenly all over the cake.
Next, smear half of the whipped cream over the jelly. Arrange the fruits and then smear another layer of whipped cream over the fruits.
Starting at the short end with straight edge, roll the cake, somewhat tight. Wrap the cake in a parchment paper and refrigerate for at least an hour, before slicing and serving.
Decoration ideas: you can simply dust powdered sugar over the rolls. Or pipe some designs with whipped cream on top.
To store, refrigerate leftover cake, covered.