Wash the cabbage thoroughly under cold water.
Shred the cabbage using a sharp knife or mandoline.
Peel and shred the carrots, then add to the bowl with cabbage.
Halve the cherry tomatoes and slice the red onion thinly.
Add the tomatoes and onion to the bowl with cabbage and carrots.
Chop the fresh parsley and mix it into the salad.
In a separate bowl, whisk together olive oil, apple cider vinegar, and Dijon mustard.
Pour the dressing over the salad ingredients.
Toss everything gently to coat with the dressing.
Season with salt and pepper to taste, and top with sunflower seeds or nuts if desired.