1. In a large mixing bowl, combine 2 cups of flour and yeast.
2. Add warm water, sugar, oil, and salt. Beat until smooth. Stir in remaining flour to form a soft dough.
3. Turn onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1 hour.
4. In a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Add cabbage, salt, and pepper. Cook until cabbage is tender. Cool.
5. Punch dough down. Divide into 12 pieces. On a lightly floured surface, roll each piece into a 6-in. circle. Top each with about ¼ cup filling. Fold dough over filling and pinch edges to seal.
6. Place on greased baking sheets. Cover and let rise until doubled, about 30 minutes. Bake at 375°F for 20-25 minutes or until golden brown.