Quarter the cabbage
Cut out that nasty core. That's not really fair. I don't know that the core is nasty. In this culture, if it's got a core, you cut it out. I'm a victim of society, don't judge me.
Now cut that quarter and half and let's do some slicing. Yes, you can use a mandolin or V-slicer. Set it to thin and you use the hand guard.
Start on a corner. As it gets wider, turn to another corner. This way your slices come in all different lengths.
Now chop your onion. Actually with this type of onion, slicing works better.
Because of the way they are grown, dirt can get deep inside the onion. Make sure you rinse them well after you chopped (sliced) them up.
Do yourself a favor; until you're ready to store this, use an extra large bowl to mix this together. You'll have an extra dish to clean, but you will be happier.
The first toss
Add your salt & pepper. I start off with 1/2 teaspoon of each. After it's been refrigerated for a couple hours you taste it and add more if needed.
Mix the red wine vinegar and olive oil until you got a nice emulsion. Shaker bottles are great for this. Or you can just make a mess like I do. Add this to the bowl and toss again.
Now transfer to the smaller bowl, put a lid on it and into the refrigerator. Sure, you could eat it now. It'll be better tomorrow though.