For the salad: Quarter and core
the cabbage. Set up a food processor
with the slicing blade. Slice the cabbage and then transfer it to a colander. Switch to the grating blade and shred
the carrots; add to cabbage. Toss the cabbage and carrots with the salt and set colander
in the sink until the vegetables wilt, 1 to 4 hours. Rinse cabbage mixture thoroughly in cold water and spin it dry in a salad spinner
Meanwhile, make the dressing
the vinegar with the honey
, mustard, celery
seeds, salt, and black pepper to taste in a small bowl. Gradually whisk in the olive oil, starting with a few drops and then adding the rest in a steady stream to make a smooth, slightly thick dressing.
Quarter, core, and shred the apples. Toss the cabbage mixture with the apples, scallions, and about 1⁄2 cup of the dressing. Refrigerate until chilled and the flavors come together, about 1 hour. When ready to serve, toss the watercress with the remaining dressing. Make a ring on a platter with the watercress
, and mound the coleslaw
in the middle of the ring.
Know-How: Salting the cabbage gives the slaw its characteristic tender bite, as well as expressing excess liquid. If you skip this step, your salad will be soggy and bland.