To prepare starter, place instant yeast in a small bowl with warm milk and sugar. Mix it well with spoon to get creamy texture. Cover the bowl with food foil and let it stand in warm place for 10 minutes. The yeast starter should double in size.
In a bowl of stand mixer with hook attachment; add flour, egg, salt and yeast starter and mix on low speed. Add slowly warm milk, until the dough gets well combined. Knead the dough with hook attachment on medium low speed for 10 minutes. If you don’t have a stand mixer, knead the dough with your hands for 10 minutes or until the dough is stretchy and soft.
Shape the dough in ball and place it back to the bowl and cover with plastic food wrap. Let the dough rise for 40 minutes to 1 hour in warm (sunny) place. The dough should double in size.
After first rise, punch the dough in the bowl. The dough will slightly deflate. Place the dough on lightly floured surface and cut it in 4 equal pieces. Shape 4 dumpling logs and place them on baking sheet, covered by plastic food wrap or parchment paper. Cover those 4 logs of dumplings with clean cotton kitchen towel and let rise for another 20 minutes in warm place.
In the meanwhile, prepare large sauce pot with steam basket. Fill it with water at the steam basket level. Brush the steam basket with butter or oil preventing sticking. Bring the water to a boil. Once the dumpling logs has risen for another 20 minutes, place 2 logs of dumplings in large sauce pot with steam basket. Cover the sauce pot with lid and lower the heat on medium-low. Steam the dumpling logs for 20-25 minutes.
Remove the dumpling logs out of the steaming basket and poke them with toot pick or fork. Cut the dumplings with sawing thread or unscented dental floss. Serve!