A few years ago I spent a winter in Bavaria, the Southeastern state in Germany. One of my favorite dishes there was Blaukraut, a simple simmered red cabbage. The dish has three different names in Germany – Blaukraut (“blue cabbage”) in the South, Rotkraut (“red cabbage”) in Central Germany, and Rotkohl (also “red cabbage” – kohl is a Northern word for kraut).
It’s believed that the different names stemmed from the fact that the cabbage can take on different colors depending on the acidity of the soil it was grown in and its method of preparation. Some contend that the variation comes from the fact that there wasn’t a German word for the color purple until after the cabbage had been introduced. Since red cabbage has a tendency to turn a blueish color when cooked, adding acid (in this case, apple cider vinegar) helps retain its redness.