Start by preparing the hardboiled eggs. Place all 4 eggs in a small pot filled with cold water and bring to a boil. Once it starts boiling, remove from the heat and cover. Let it sit for 6 minutes before running them under cold water. Peel each egg and leave aside.
In a small bowl, combine all the ingredients needed for the cucumber sauce and keep it in the fridge.
Place the salmon slices on a large plate and season with 2 Tbsp of olive oil and dried dill.
Slightly toast the bread slices and generously slather with butter while still hot.
Time to assemble the sandwich! Top each slice of bread with: lettuce, slices of avocado, a slice of tomato, a slice of smoked salmon and an egg (cut in half). Garnish with a generous amount of cucumber mayonnaise sauce, a slice of lemon and a sprinkle of dried chives.
Season with salt and pepper (to taste).