To make the pickled onions, place the sugar, salt & vinegar in a jar or small bowl and mix to combine. Add the sliced red onion and toss to coat. Add enough boiling water to just cover the onions and set aside to quick pickle.
To boil the eggs, bring a small pot of water to a boil. Gently lower the eggs into the water and cook for 7 minutes. Immediately transfer the eggs to a bowl full of ice water and leave to cool completely before peeling and cutting into ¼’s.
To assemble, spread each of the rye bread slices with a tablespoon of mayonnaise. Top each toast with 1 slice of cold smoked salmon, 2 slices of beetroot and 2 pieces of the boiled eggs. Garnish with the diced gherkins, pickled onions and a sprinkle of fresh dill.