Make the dough
Whisk together the sugar, yeast and water in your mixing bowl. Let sit for 5 minutes to “proof” (meaning to check and make sure your yeast is active before you waste any more ingredients!) The yeast, sugar and water should start to bubble just a bit.
Stir in the milk, oil, 1/4 tsp salt and eggs. Put about 3 cups of the flour into the bowl and turn the mixer on to a low setting. Let the mixer incorporate most of the ingredients together then add the last cup of flour, about 1/4 cup at a time until it pulls away and makes a nice elastic-looking ball. Keep the mixer on for 5 more minutes or so.
Rub a bit of oil in the bottom of a bowl and turn the dough into that bowl, flipping it around and turning it so that all sides are coated very lightly with oil. Cover the bowl with a clean kitchen towel and let rise until doubled, about an hour. (If you kitchen is really cold, you can turn the light on in your oven and let it rise there. The light bulb will provide a bit of warmth.) After the dough has doubled in size, punch it down and let it rest while you make the filling.
Make the filling
In a skillet, heat the oil then add the onion and ground meat. Cook,stirring, until the onion is softened and the meat is no longer pink. Add the cabbage and cook a few more minutes until the cabbage wilts. Salt and pepper the meat mix and set aside to cool, covered, while you roll out the dough.
Put it together
Cover a cutting board or counter with a light dusting of flour. Divide the dough in half and roll one half into a roughly 10 x 7 inch rectangle. Cut this into six squares and place about 1/4 cup of the meat and cabbage mix into the middle of each square.
bierrocks foldingPull two opposite corners together and pinch together, then do the same with the other two corners. Place seam side down onto a baking sheet lined with parchment paper. Repeat with the other half of the dough.
Preheat the oven to 375 while you cover the bierocks again and let rise about 20 minutes.
Uncover and bake about 15 minutes. Cool a bit on wire racks then serve.