Sift the flour, buckwheat flour and baking powder into a bowl. Make a well in the centre of the dry ingredients. Beat the egg, then beat in the buttermilk and melted butter. Pour into the well, add the chopped dill and stir gently until the ingredients are just mixed. Heat a frying pan over a medium heat. Lightly grease the pan with oil spray. Drop in teaspoonfuls of the mixture. Turn the blini when small bubbles appear on the surface and the underside is golden brown. Cook until the second side is golden brown. Cool on a cake rack. When cold, spread each blini with Crème Fraîche, top with a piece of smoked salmon and garnish with dill sprigs. Makes about 24.