Sift flour into a bowl and form a well in the middle. Mix together yeast, 1 teaspoon sugar, some lukewarm milk and a little flour into a viscous wet sponge. Pour into well in flour bowl, sprinkle with flour and cover for about 30 minutes. Let the dough rise. Add soft butter, the remaining sugar and lemon zest to the flour at the bowl's edge and add the remaining milk and an egg to the center of the well. Work from the center outwards to incorporate the flour with the remaining ingredients. Knead dough as long as needed until it unsticks from the edge of the bowl. Cover and let rise for 30 minutes. Then knead again and form individual rolls with a tablespoon. Brush baking dish with melted butter and flip rolls into it. Set rolls next to each other and allow to rise for 30 minutes.
Bake in preheated oven at 180°C (approximately 360°F) convection about 25-30 minutes or until golden brown. Remove and allow to cool slightly. Dust with powdered sugar and serve lukewarm.