Prep veggies: Prepare the cabbage, onion, and carrots as instructed in the ingredients section above. Then get out a large bowl, and toss them into it.
Make the vinaigrette: Add the ingredients for the vinaigrette to a small nonaluminum pot, and place it over medium heat. Stir the mixture for a minute or two until the sugar has dissolved, and the liquid has slightly begun to boil.
Pour on slaw: Pour the warm vinaigrette onto the veggies, and add the celery seeds. Then toss this all together until the vinaigrette covers everything evenly.
Let it sit: We want to let the coleslaw sit for at least a couple of hours so that the flavors of the vinaigrette can fully develop. Now technically because the slaw doesn’t have any mayo, it is safe to sit a room temperature, however, I prefer my coleslaw cool so I tend to let it rest in the fridge for this step.