Place the mashed potato in a mixing bowl. Beat in the flour, egg yolks, soured cream and dill and season well.
Whisk the egg whites until stiff. Using a metal spoon, carefully fold the beaten egg whites into the potato mixture.
Heat a little oil in a large, nonstick frying pan. Add 3–4 separate tablespoons of the potato blini mixture. Fry over medium heat until set, then turn the potato blinis over and fry briefly so that both sides are lightly browned. Remove and keep warm. Repeat the process until all the potato mixture has been used.
Meanwhile mix together the beetroot, crème fraîche and creamed horseradish and season well.
To serve, spoon the beetroot mixture over the blinis, garnish with chopped chives and freshly ground black pepper.