Heat oven: To 325°F (165°C).

Make the cake layers: Coat the bottom of 2 9-inch round cake pans lightly with nonstick spray and line each pan with a fitted circle of parchment. Do not spray the sides of the cake pan. Lightly coat two cooling racks with nonstick spray, too; you’ll use them later.

In one large bowl, whisk together yolks, lemon zest, and 1 cup of the granulated sugar. It will seem stiff and dry at first, but keep whisking (1 minute) and the batter will loosen and become a pale yellow and thick like frosting. Whisk in oil, then water and vanilla extract. Sprinkle half of flour over batter, then salt and baking powder, followed by second half of flour. Whisk to combine, until smooth. This batter will be very thick for now.

In a second large bowl, use an electric mixer to beat the egg whites until thick enough to hold firm peaks. Add remaining ¼ cup sugar gradually, beating the whole time. Continue to beat egg whites until very thick and holding firm peaks; when you pull the (turned off) beaters away, the tip of the peaks will flop over slightly. Add lemon juice and beat to combine.

Add ¼ of egg whites to yolk mixture and whisk to combine; you’re just using this to loosen the batter. Carefully fold the remaining egg whites in in two additions, doing your best to not deflate them.

Divide the batter between the two prepared pans and bake for 20 to 25 minutes, until a toothpick inserted into the center of the cake comes out clean.

As soon as you remove each layer from the oven, drop it a few times onto your counter from a few inches above. Cool cake layers completely in their pan upside down on the cooling racks you sprayed earlier.

Assemble the cake: With an electric mixer, whip heavy cream, powdered sugar, and vanilla until soft peaks form. Add sour cream or crème fraîche and beat until mixture is thick enough to hold shape, but creamy and not grainy.

When cake layers are completely cool, carefully flip pans back over. Run a knife around each cake layer, separating it from the sides of the pan, and turn out onto a rack. Using a long, serrated knife, carefully cut each cake layer into two thinner layers.

Place first cake layer on a serving platter or cake stand. Spread one slightly heaped cup of whipped cream over the layer and arrange approximately one-quarter of the sliced strawberries over the cream. Repeat this process three times.

To serve: Serve the cake in wedges.