Preparation:

Bring stock to a boil and add rice. Simmer until tender, about 20 minutes. Season stock to taste with salt, if necessary.

When the rice is nearing tenderness, whisk the egg whites in a separate bowl until medium peaks. Add egg yolks and lemon juice, whisking continuously.

When the rice is finished, transfer 2 cups of the hot stock to the egg/lemon mixture, adding very slowly in a constant stream and beating vigorously to prevent the eggs from solidifying.

Take the soup off the heat and add the beaten mixture back into the pot, whisking to incorporate. Serve immediately with freshly ground black pepper.