For the Dressing:
1/2 cup (120ml) apple cider vinegar
1/4 cup granulated sugar (1.75 ounces; 50g)
3 tablespoons (45ml) extra-virgin olive oil
1 teaspoon finely minced garlic (about 1 medium clove)
1 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume
Freshly ground black pepper
1 teaspoon celery seeds
For the Slaw:
1 large head green cabbage (about 3 1/2 pounds), finely shredded on a mandoline or by hand (16 cups)
2 large carrots (6 ounces; 170g), peeled and grated on the large holes of a box grater (1 cup)
1 medium yellow onion (8 ounces; 225g), thinly sliced crosswise on a mandoline or by hand (1 cup)
2/3 cup sugar (4.7 ounces; 133g)
1/3 cup Diamond Crystal kosher salt (1.7 ounces; 48g); for table salt, use half as much by volume or the same weight