In a bowl whisk together mayonnaise and butter and stir in eggs, celery, onion, lemon juice, and salt and pepper to taste. Spread mixture in an oiled 9-inch springform pan and sprinkle evenly with scallion greens, chives, and dill. In a small bowl stir together cream cheese and sour cream until smooth. Drop dollops of cream-cheese mixture over herbs and spread carefully (keeping herb layer intact) to form an even topping. Chill torte, covered, at least 8 hours and up to 1 day. Just before serving, run a thin knife around edge of pan and remove side. Transfer torte to a serving plate and spread caviar over top. Garnish torte with dill sprigs and serve with toast points. Serves 12. Gourmet September 1994