How to Make It
In a food processor fitted with the julienne blade, cut the celery root into julienne strips.
In a large bowl, stir the salt with the lemon juice. Add the celery root and toss to coat thoroughly. Set aside for 30 to 45 minutes.
Meanwhile, make the remoulade. In a blender or food processor, combine the mustard and ginger and process until smooth. Add 1 1/2 tablespoons of hot water and pulse to combine. With the machine on, slowly add the oil and vinegar and blend until the sauce is smooth and emulsified. Season with salt and white pepper to taste.
Drain the celery root julienne; rinse well and pat completely dry. Transfer the celery root to a bowl and toss with the remoulade sauce. Cover and refrigerate for at least 1 hour. Serve chilled.