Bohemian plum jam liwanzen (Small, fried yeast pancakes)

Dissolve the yeast, sugar and salt in the lukewarm milk. Stir in the sifted flour, making sure the batter is smooth. Then add the egg yolks, vanilla pod, lemon rind and melted butter. Cover, and leave to rise for 1 hour at roomtemperature.Whisk the egg whites until stiff and fold into the batter. In a liwanzen pan (cast iron frying pan with round hollows), heat the butter and pour the batter into the hollows. (If you don’t have a liwanzen pan, usemetal rings about 6 cm Ø in a teflon-lined pan). Shake the pan so that the batter is evenly spread. Allow the liwanzen to cook for about 5 minutes on one side, turn over and finish cooking.
Remove, and brush half of the liwanzen with plum jam and sandwich with one without jam. Caramelize the sugar in a pan, and dribble over the liwanzen. Serve dusted with icing sugar.