To make the cabbage and mince filling, cut the cabbage into quarters.
Steam until very tender, about 20 to 30 minutes, drain and cool.
Working in small batches, wrap cooled cabbage in a towel and squeeze out as much liquid as possible.
Chop squeezed cabbage finely in a food processor, transfer it to a large mixing bowl, add softened cream cheese, 4 tablespoons melted butter , pinch of ground fennel and salt and white pepper to taste.
Lightly fry the mince with a pinch of salt until browned, put aside to cool and then add to mixture.
Mix until combined.
Dough Mixture In a medium bowl whisk egg.
Add sour cream and whisk until smooth.
Add milk and 1 cup water, whisk till combined.
Slowly add about 3 cups flour and stir to combine with a wooden spoon.
Turn dough out onto a floured surface and work in about 1 cup flour as you knead.
Use a plastic scraper to lift the dough which will stick to the counter before flour is worked into it. Continue kneading for about 8 to 10 minutes, working in another .5 cup flour. The dough should be elastic in texture and no longer sticky. Be careful not to add too much flour as this will toughen dough. Place dough in a lightly floured bowl, cover with plastic wrap and let rest.
On a floured surface, roll out dough to about 1 to 2mm thickness.
Using a glass or cookie cutter measuring 7 to 8 cm diameter, cut out as many circles as possible. Gather scraps together, reroll and continue cutting.
Fill a glass with some water to have next to you.
Form filling into 2.5 cm balls and place a ball in the center of each dough circle in your hand, wet your finger and dampen the half circle edges, fold dough over filling and pinch the edges, forming a well sealed crescent.
Place on a linen towel sprinkled with cornmeal. Continue this process until all dough circles are filled.
Place pierogi in salted boiling water in batches. They will sink to the bottom of the pot and then rise to the top. Once they rise, let them cook for about 1 more minute. Place on a linen towel to dry and cool down.
These are now ready to freeze in a plastic bag.
To serve, defrost pierogi and fry batches in a pan of diced onions and two knobs of butter, season with salt and white pepper.
