1) Preheat the broiler to high and line the broiler rack with foil. Cut the tomatoes in half and scoop out the flesh and seeds. Chop the flesh finely, then place in a strainer to allow the excess liquid to drain away.
2) Cut the smoked salmon into small pieces. In a separate bowl, beat the eggs, egg white, and water with pepper to taste. Heat a nonstick small pan and when hot, add the beaten egg. Cook for 1 minute, stirring continuously, then stir in the drained tomato flesh and the smoked salmon. Continue to cook, stirring for 3 to 4 minutes, or until the eggs are set to personal preference.
3) Meanwhile, place the halved tomatoes on the broiler rack and broil for 2 minutes. When the egg mixture is set, use to fill the warm tomato shells. Sprinkle with snipped chives and serve two tomato cups per person.