Taste the dressing before you toss it with the slaw so you can get the sweet-to-vinegar balance right. Store leftovers in an airtight container in the fridge for 3 to 4 days, though it's crispest in the first day or two. To make it well ahead, keep the dressing and the slaw mix separate and toss them together an hour or two before serving so the cabbage stays crunchy.