Potato Holubtsi Filling with Buckwheat Groats

4 large potatoes

1 small onion, diced

2 Tbsps. butter

½ cup sour cream

½ cup medium buckwheat groats

Salt and pepper

1 cup sour cream

Pare and grate the potatoes on a fine grater. Put them into a sieve, and drain as much liquid as possible. Cook the onion in the butter until tender. Combine it with the potatoes. Add the sour cream. Pour boiling water over the buckwheat groats and drain them over a sieve. Repeat this washing twice. Drain the groats well and add to the potato mixture. Season to taste, with salt and pepper. Use cabbage leaves with this filling. Pour 1 cup of sour cream over the holubtsi and bake in a moderate oven (350 F.) for 1- ½ hours. Serve hot with sour cream or with a sauce made by cooking a diced onion in sour cream.