Add the cabbage, carrots and green onions to a large bowl.
Whisk together the dressing ingredients in a separate medium bowl. Taste and add additional vinegar for tangier or it it's too tart and you prefer a sweeter coleslaw, stir in additional sugar.
Pour the dressing over the coleslaw and toss to evenly combine.
Cover and refrigerate until ready to serve, best if 1-2 hours after combining. Taste again before serving and adjust to taste. For a creamier coleslaw, stir in additional mayo/sour cream.