Place the eggs in a small, heavy saucepan with a tight-fitting lid and add cold water to cover by 1 inch. Bring to a boil over medium-high heat, then turn off the heat, cover the pan with the lid and let stand for 10 minutes. Remove the eggs and place them in a bowl filled with ice water. When cool, peel the eggs and finely chop in a medium bowl. Add the salmon, chives, mayonnaise and sour cream. Season to taste with salt and pepper.
Spread one-third of the egg salad on each of 3 slices of bread. Cover with the remaining bread slices. Trim the crusts and cut each sandwich into 4 triangles.