Preheat the oven to 340°F (170°C). Line an 8-inch/20 cm round cake pan with parchment paper.
In a stand mixer fitted with a whisk attachment, beat the egg whites on medium speed for about a minute. Gradually add the sugar and continue beating for about 7 minutes, until stiff, glossy peaks form. Reduce the speed and mix in the egg yolks and oil. Stir in the orange juice.
Sift the flour and baking powder into the batter. Using a whisk, fold gently until smooth and airy. Pour into the prepared pan and bake for about 45 minutes, or until a toothpick inserted in the center comes out with moist crumbs. Let the cake cool completely.
In a small saucepan, bring the sugar, water, and orange zest to a boil. Let cool and refrigerate.
For the mascarpone cream, beat the mascarpone in a stand mixer for a minute to soften. Add the heavy cream, powdered sugar, and vanilla. Whisk on medium speed until thick and stable.
Wash and halve half of the strawberries. Dice the remaining half into small cubes.
Slice the cooled cake horizontally into two layers. Place one layer in an 8-inch/20 cm cake ring or the same pan used for baking. Brush with syrup.
Arrange halved strawberries around the edges, flat side facing out. Spread a layer of mascarpone cream evenly over the cake base. Scatter the diced strawberries on top. Brush the second cake layer with syrup and place it over the filling. Refrigerate for at least 2 hours before unmolding. Slice and serve chilled.