1. Preheat & Prep: Get your oven ready to 350Β°F (175Β°C). Lightly spray a 12x17 inch baking sheet with nonstick baking spray. Line it with parchment paper, then gently grease the parchment with a little butter. Set aside.
2. Whip the Whites: In a medium-sized bowl, beat your room-temperature egg whites on medium-high speed until they form soft peaks, about 1-2 minutes. Gradually add one-third cup of the granulated sugar and keep beating until stiff, glossy peaks form (another 1-2 minutes). Set this fluffy mixture aside.
3. Mix the Yolks: In a separate medium bowl, whisk together the egg yolks, vegetable oil, milk, the remaining two-thirds cup of granulated sugar, 1 teaspoon of pure vanilla extract, and 1 tablespoon of lemon zest until smooth and combined.
4. Combine Dry Ingredients: In a small bowl, whisk together the flour, cornstarch, baking powder, and salt.
5. Fold Batter: Slowly add the dry flour mixture into the wet egg yolk mixture, stirring gently until just combined.
6. Lighten the Batter: Carefully fold the whipped egg whites into your cake batter until everything is just blended. Don't overmix!
7. Bake the Cake: Pour the light batter onto your prepared baking sheet and spread it evenly. Bake for about 15 minutes, or until the top is lightly golden brown. Let the cake cool completely on the baking sheet β no need to roll it warm with this easy recipe!
8. Prepare Strawberries: While the cake cools, gently mix the sliced fresh strawberries with 1 tablespoon of sugar and 1 tablespoon of lemon zest in a small bowl.
9. Whip the Cream: In a large, chilled bowl, beat the heavy whipping cream on high speed until soft peaks begin to form. Add the light sour cream, Β½ teaspoon of pure vanilla extract, and ΒΌ cup of powdered sugar. Continue beating until you have firm, fluffy peaks.
10. Assemble the Roll: Once the cake is fully cooled, spread the whipped cream filling evenly over the entire surface, leaving a 1-inch border around the edges. Scatter your sweetened strawberries over the cream.
11. Roll It Up: Starting from one of the shorter ends, carefully roll the cake up, gently peeling away the parchment paper as you go.
12. Serve with a Flourish: Place the rolled cake seam-side down on a serving platter. For an elegant touch, dust lightly with extra powdered sugar just before slicing and enjoying!