Dust the walnuts with the paprika or cayenne then dr-fry them in a heavy-based frying pan. While still hot coat them with the honey and cool.
Wash and peel the apple, celeriac and beet, then cut them into matchsticks (or use a food processor with a shredder blade if you have one).
Squeeze the lemon into a bowl of water then put the apple and celeriac into this mixture.
Put the beetroot into a large mixing bowl. Thinly slice the spring onion, then add to the beets.
After 5 minutes or so drain the apple and celeriac. Wrap them in a clean kitchen towel for a couple of minutes, then add to the beet.
Meanwhile toss together the dressing.
Add the honey-walnuts and dressing to the slaw, then season with salt and pepper to your liking.