Working quickly, peel the celery root and cut into chunks. Use spiralizer to make into noodles or Grate finely in a food processor fitted with the shredding blade and immediately toss with the salt and lemon juice. Set aside.
Place the mustard in a mixing bowl and, while whisking, slowly drizzle in the hot water. When the water is completely incorporated, drizzle in the oil until completely incorporated. Add the vinegar, little by little, to form a smooth emulsion and season with white pepper. Stir in the herbs and dill pickle.
Add the dressing to the celeriac, to taste. Serve immediately or allow to sit, refrigerated, in a sealed glass or plastic bowl, for 2 hours and up to 2 days.
If you are following an Ideal Protein protocol: One serving (half) of this recipe counts as 1 cup of select vegetables.