1. Puree the fish with the egg whites in a blender or food processor, then rub the mixture through a sieve into a bowl.
2. In a clean bowl, whip the cream to the same consistency as the fish puree. Fold the cream into the pureed fish lightly but thoroughly. Season the mixture with salt, pepper and nutmeg, cover the bowl and chill for several hours.
3. The chilled quenelle mixture is shaped and cooked in one operation. Prepare a large saucepan of hot water and place a large dinner plate on top of it: this will be used to keep the quenelles hot as they are cooked and before they are served. As soon as the first quenelle is placed on the hot plate, turn the heat off under the saucepan to prevent further cooking.
4. Heat the court bouillon in a large saucepan until just simmering: the surface should just quiver. Using 2 rounded dessertspoons shape the chilled mixture into ovals, and gently lower these into the liquid. To obtain a neat oval, scoop a portion of mixture cleanly from the bowl. Use the second spoon to cup the top of the portion, then slide the spoon over the mixture to scoop it from the first spoon. This technique of passing the mixture from one spoon to another makes the oval shape.
5. Simmer the quenelles for 8-10 minutes, then carefully remove with a slotted spoon.
6. Transfer the quenelles to the plate over the saucepan of hot water as they are cooked. Cover loosely with foil to keep hot until all the mixture is cooked.
Serve the quenelles immediately, with Fresh Tomato Sauce