Cabbage Filling for Varenyky Pyrohy

1 medium head cabbage           

4 Tbsps. butter

1 medium onion, diced  

1 Tbsp. lemon juice

Salt and pepper

Remove the outer leaves and core from the cabbage. Cut the cabbage in coarse pieces and cook it, uncovered, in boiling water for about 6 to 8 minutes, or until the cabbage is barely done. It should retain some crispness. Drain, cool, squeeze very dry, and cut the cabbage very fine. Cook the onion in butter until it is tender. Add the cabbage, lemon juice, and season to taste. Cook these ingredients for a brief period to blend the flavours. Chill thoroughly.