Make the dough: soften the yeast in warm water in a bowl.
Mix flour with sugar and salt. Cut in the butter until mixture has a fine, even crumb.
Beat eggs and extra yolks; mix with yeast, then stir into the flour mixture. Add the sour cream and the vanilla and mix well.
Knead dough on floured surface for 5 minutes. Divide in half and roll each half into a 12 inch square. Cover.
Make the filling: melt butter in a large pan. Add poppy seed and stir-fry for 3 minutes.
Add honey, lemon juice, and raisins to poppy seeds. Cover and remove from heat. Let stand for 10 minutes.
Beat egg whites with sugar until stiff moist peaks form. Fold in orange and lemon peels and then gently fold in poppy seed mixture.
Spread half of the filling on each dough square (after you uncover them). Roll up as you would for a jelly-roll and seal the edges. Place on greased baking sheets and cover. Let rise until doubled in bulk (approx. 1 1/2 hours).
Preheat oven to 350 degrees. Bake about 45 minutes, then remove from oven and cool.
Make the icing: mix powdered sugar and lemon juice until smooth. Spread this mixture evenly over the rolls.
Notes: You can grind poppy seeds in a mortar and pestle. Specialty food stores sell grinders specifically designed for poppy seeds. Some spice shops sell poppy seeds already ground, but like all spices they lose their freshness much more rapidly after they are ground.