Mix the flour and salt in a bowl. Stir the yeast into the milk, add to the flour. Add the butter and egg yolk and stir everything together to form a smooth batter. Cover the batter and leave to rest at room temperature for approx. 1 hr. Heat a little butter in a frying pan. Fry 10 blinis in the butter, each approx. 5cm, on both sides for approx. 2 1/2 mins. each side.
Coat the blinis with the maple syrup and garnish with crème fraîche and caviar.