1) Add the cabbage, carrot, parsnip, celeriac, apple and parsley to a bowl
2) In a separate bowl combine the mustard, olive oil, honey, lemon juice, and cider vinegar and whisk until smooth and mixed well.
3) Pour the mustard mix over the cabbage mix, season with salt and pepper and mix well so the dressing has covered all the vegetables evenly.
4) Cover and place in the fridge for 10 minutes.
5) Remove from the fridge, give another good mix, transfer to a serving bowl and serve