1-First Step: Prep the pan and oven Preheat your oven to 350 degrees Fahrenheit. Spray a baking sheet with nonstick spray, line it with parchment paper, and grease the parchment with butter. This helps the cake release cleanly after baking. Good pan prep matters because a cake roll needs to be flexible, not stuck to the tray.

2-Second Step: Whip the egg whites Beat the egg whites on medium-high speed until soft peaks form, which usually takes 1 to 2 minutes. Add 1/3 cup of the sugar, then keep beating until stiff peaks form, about 1 to 2 more minutes. Set the bowl aside. Room temperature eggs help the whites gain better volume, which gives the cake its light texture.

3-Third Step: Mix the yolk base In a separate bowl, whisk together the egg yolks, vegetable oil, whole milk, vanilla extract, remaining 2/3 cup sugar, and lemon zest. This mixture should look smooth and glossy. The lemon zest gives the cake a fresh flavor that works so well with sweet strawberries.

4-Fourth Step: Add the dry ingredients In another bowl, whisk the flour, cornstarch, baking powder, and salt. Then gently stir the dry mixture into the wet mixture. Mix only until combined. Overmixing can make the cake less tender, so keep the motion soft and light.

5-Fifth Step: Fold in the egg whites Fold the beaten egg whites into the batter until just combined. Use a gentle hand so you do not lose the air you whipped in earlier. That air is what gives the sponge its lift and helps it roll without tearing as easily.

6-Sixth Step: Bake the sponge Spread the batter evenly on the prepared baking sheet. Bake for about 15 minutes, or until the top is light brown. The cake should spring back when lightly touched. Let it cool completely before filling. Cooling is important because warm cream will melt, and a warm cake can also shift during rolling.

7-Seventh Step: Make the strawberry filling While the cake cools, combine the strawberries, sugar, and lemon zest in a small bowl. Stir gently so the berries stay mostly intact. This step brings out the juices and gives the roulade a fresh, juicy center. Use fresh strawberries when possible for the best texture and color.

8-Eighth Step: Whip the cream filling Beat the heavy whipping cream until soft peaks form. Add the sour cream, vanilla extract, and powdered sugar, then beat until stiff peaks form. The sour cream adds a little tang that keeps the cream from tasting too sweet. For a richer understanding of dairy desserts, you can also read this heavy whipping cream guide from WebMD.

9-Ninth Step: Fill the cake Once the cake is fully cool, spread the whipped cream mixture over the surface, leaving a one-inch border around the edges. Scatter the strawberry mixture on top. Do not overfill the cake, or the filling may spill out when you roll it.

10-Tenth Step: Roll and finish Starting at the short end, roll the cake carefully, allowing the parchment to fall away as you go. Place the roll seam side down. Dust with powdered sugar if you like. Slice and serve chilled for the neatest cuts and best texture.