Brown ground beef and minced onion in a heavy skillet with a small amount of oil.

Add minced cabbage, salt, and pepper to the skillet.

Steam the mixture until the cabbage is tender and lightly browned. Let it cool completely.

Roll thawed bread dough to 1/4 inch thickness and cut into 2 1/2 inch squares.

Place 2 heaping tablespoons of the beef and cabbage mixture in the center of each square.

Place another square of dough on top of the filling and pinch the sides together to seal.

Brush the top of each piroshki with a little butter.

Place the piroshki in a greased pan.

Let them rise for 15 to 20 minutes.

Bake at 350 degrees Fahrenheit (175 degrees Celsius) for 25 to 30 minutes, or until golden brown.