In a large mixing bowl, combine the flour, salt and baking powder. Pour in the olive oil, warm water and beaten egg. Mix well with a fork or pastry blender. Knead the dough for about 5 minutes or until smooth and elastic. Form into a ball. Cover with a clean towel and let rest for 10 minutes.
Divide dough into thirds and roll out onto floured surface to 1/8" thickness. With 3" cutter or glass, cut out circles.
Fill each circle with a Tablespoon of sauerkraut. Fold over and seal edges with the tines of a fork dipped in flour.
Fill a medium stockpot with water and add 1 Tbsp. salt. Bring to a boil and drop pierogies in (I like to work with 5 to 6 at a time). Let boil for two to three minutes. When pierogies float to the surface, remove with a slotted spoon and let drain on paper towels. If you plan on freezing them, place on a cookie sheet in a single layer and freeze for one hour. Remove from freezer and place in freezer containers or gallon freezer bags. These will keep for 6 to 9 months frozen and will need to be thawed for at least 30 minutes before browning.
Melt 1/2 cup of butter in a large skillet over medium heat. Add pierogies and brown. Turn and brown the other side. Keep warm.
Melt the 1/4 cup of butter in the skillet and add the onions.
Saute, stirring occasionally, until the onions are browned and soft. Add the 1/8 cup of wine to deglaze the pan.
Serve pierogies topped with caramelized onions. This recipe makes 30 pierogies.