Pour the flour into a large mixing bowl and use your fist to make a well in the top.
Sprinkle the yeast over 4 tablespoons warm milk. Pour this mixture into the well in the flour, add 1 tablespoon sugar, cover with a little flour, and let stand for 15 minutes.
Mix the dough with 1/2 cup milk, the eggs, 1/4 cup sugar, grated lemon peel, and a small pinch of salt.
Pour in the 5 Tbsp cooled melted butter, and knead into a dough. Cover and let rise, about 1 hour, knead briefly, and then let stand once again so the dough has another chance to rise.
Prepare the poaching liquid: Combine the 2 Tbsp butter, 1/2 cup milk, 1 Tbsp sugar, and a small pinch of salt in a large pot with a tight-fitting cover, stir well, bring to a boil and turn off the heat.
Roll the dough into little balls and place these closely together inside the pot. Cover the pot tightly, leaving ample space for the dumplings to rise. Check that the lid fits tightly enough so that none of the steam can escape. (If necessary place a clean dish towel between the edges of the pot and the lid to form a tighter seal.)
Cook the dumpling over medium heat for about 20 minutes. No peeking! When the dumplings are done and all the liquid absorbed, the bottom crusts of the dumplings will make a faint crackling sound. Then (and only then) remove the cover. Take out the dumplings with a spatula. Serve immediately.