Light Lemon Mousse

2 tablespoons unflavored gelatin

3 to 4 lemons

5 large eggs, separated

1 1/3 cups sugar

2 cups heavy cream

Pinch cream of tartar

6 to 8 ounces raspberries or strawberries, stemmed

Mint sprigs, for garnish

Place 1/2 cup water in a small saucepan and bring to a simmer. Remove it from the heat and sprinkle with the gelatin; whisk until dissolved. Let cool slightly. Grate the zest from three of them lemons and set it aside. Squeeze 2/3 cup juice from the lemons, using the fourth one if needed; set aside.

In a large glass or ceramic bowl, combine the egg yolks and sugar; beat with an electric mixer at medium speed until pale in color, stopping occasionally to scrape down the sides of the bowl with a rubber spatula. Add the grated lemon zest and continue beating. Gradually beat in the lemon juice and set aside.

In a metal bowl, using the mixer, whip the cream until soft peaks form. With a rubber spatula, fold the cream into the lemon mixture. Add the gelatin and continue folding until the mixture begins to thicken. Set aside.

Place the egg whites in a clean bowl and add the cream of tartar. Using the mixer, with very clean beaters, beat the whites until stiff. Fold the whites into the reserved cream and lemon mixture.

Place some raspberries or strawberries in the bottom of individual goblets or bowls and divide the mousse among them. Cover and refrigerate until well chilled, at least 4 hours. Serve garnished with mint sprigs.