>>>outsourced the red kraut and the dumplings to the wifes ...
>My late wife, whose first language was German, also said "red kraut" or "red cabbage" when speaking English, but "blau kraut" when speaking German.
>I always thought that "purple kraut" would have been most accurate, but that blue was closer to the real color.
>How do you say it in German?

Aargh

Depends on where you are in germany. It's Rotkohl (red cabbage) or Blaukraut (blue kraut) with Rot and kohl more in the north and Blau and kraut more in the south of the german language area.

The correct color is violet or better lilac, but lilac is a late inheritance out of arabic. Earlier we had only red and blue.
Since the cabagge changes it's color due to pH, its sometimes more red or blue a) on the soil and b) on the food preparation. Infact it's used as an good example for pH testing.

Maybe your wife is from the Blaukraut (Southerners? Bavarian? Just kidding...) area and looked up the translation to english what comes up to red cabagge.

I'm on the Rotkraut fraction. :)
We first fry (schmalzen. no idea how to translate, turn around in the hot lard?) it a bit in pork or goose lard. Then we steam it in a vinegar-salt solution. A onion larded with cloves. It comes crisp and tasty.