Mix the shredded cabbage and sliced onion in a large bowl.
To make the dressing, boil the remaining ingredients on stove, whisking to combine until sugar has dissolved completely.
Pour hot dressing on top of cabbage and onions; stir to coat.
Refrigerate for at least two hours before serving; stirring occasionally to redistribute dressing.
Make ahead: This coleslaw will keep in the fridge in an airtight container for up to three days, but I think it's best served 12-24 hours after making it.
Ingredient substitutions: I do not recommend using honey instead of sugar, or any other kind of vinegar. You can, however, use another kind of onion or cabbage, if you want, or add other veggies like shredded carrots. You can also use another kind of oil, like vegetable or canola, in place of the olive oil.
How to serve it: I recommend serving this on top of pulled pork sandwiches or fish tacos, or as a side for a BBQ.