Spread out half of the bread slices and cover with the smoked salmon, cutting the slices to fit, as needed. At the centre of each sandwich, place 1 tsp of the fish roe. Place 1 egg half, cut side down, over the fish roe. Cover the remaining bread slices with the mashed egg mixture. Close the sandwiches. Cut the sandwiches into two rectangles, making sure to cut through the egg lengthwise. Wipe down the knife between each cut.