Sausage and Cabbage Stir Fry

Based upon this recipe by Richard Nikoley:

• 1/2 head green cabbage
• 1/2 head purple cabbage
• 1/2 red onion
  
• large link of Polish sausage (Richard recommended uncured sausage, if you can find it)
• 1 tsp coconut oil

Heat oil in wok on high. Add onions. Stir for 30 seconds. Add cabbage and sausage. Stir fry for 5 minutes or until vegetables are desired crunchiness.

As you can see, I added too much coconut oil (it was my first attempt at cooking with it). Also, the color from the purple cabbage bled into everything else. The same thing happened when I used the remaining half to cook with potatoes and carrots—when I fixed a corned beef dinner. The purple potatoes freaked out my son. I don't know if there is a way to prevent that, such as blanching it first. I'll have to experiment with it.

Incidentally, my wife thinks my wok is aluminum, and worries her that cooking with it could increase the risk of Alzheimer's. I think it's carbonized steel, but there is no imprint on it. If anyone knows how to tell the difference, let me know.