In a bowl, combine mayonnaise, sour cream, green onions, mustard, black pepper and lemon zest.
Peel the eggs. Cut two eggs in half, take out the yolks, remove them (use at your own discretion in other dishes). Finely chop the whites together with the rest of the whole eggs. Place the chopped eggs in a bowl with the dressing and stir.
Place 4 slices of bread on a plate, on each of them put ½ cup of egg salad, a slice of bacon, 2 slices of tomato and 1 lettuce. Cover with the remaining bread slices. Serve the sandwiches immediately.