Sauerkraut is roughly translated to "sour herb" in German and basically is a pickled/fermented shredded cabbage. The shredded cabbage is pickled in a process called lacto-fermentation. Lactic acid is added to the shredded cabbage and over the course of the fermentation process the acid breaks down the sugars in the cabbage and "cures" it. Once cured, the cabbage can be stored for months.
Polish Sauerkraut
2 pounds sauerkraut (in bag)
1/2 cup bacon; chopped and cooked
3 cups water
1/2 teaspoon salt
1/2 teaspoon pepper
1 teaspoon caraway seed
1/4 cup carrots; shredded
1/2 cup butter
1/4 cup lard
1/4 cup flour
1. Rinse sauerkraut with cold water for several seconds and drain well. Taste and test for sourness. Rinse again if necessary.
2. In a large pot, combine pepper salt, caraway seeds, shredded carrots, and water. Add browned bacon to the pot. Bring to boil. Cook uncovered over medium heat for 30-45 minutes.
3. In a skillet, melt butter and lard, while stirring add flour. Keep stirring until mixture (rue) turns light brown.
4. Slowly add mixture to the sauerkraut stirring constantly to prevent clumping. Cook 10-20 minutes stirring occasionally. Add salt and pepper to taste