This is a Greek-style slaw that goes particularly well with grilled meats, chicken or fish; the key ingredient is white vinegar.
1 medium head green cabbage, sliced very thin
1/2 medium red onion, sliced very thin
1/4 c olive oil
1/4 c white vinegar
1 t Kosher salt
1/4 t ground black pepper
Method: Dump the cabbage into the bowl you will use for serving; mix salt and vinegar to dissolve in a jar, add oil to the jar and shake; pour over cabbage; mix well; add onion on top. Refrigerate at least 1 1/2 hours, taste and correct the seasoning if you like, then serve. The slaw will seem dry at first but will become more moist as the cabbage throws off its juice.
Variations: since this is a Greek-influenced slaw you could experiment with any of these Greek-style add-ins:
1/4 t ground cumin, or 1/2 t whole cumin seeds
2 T chopped fresh mint
1 t dried oregano