Step 1

Combine the mustard and vinegar and whisk together. Add the oil in a slow, steady stream, whisking constantly, until combined. Season with salt and pepper to taste. Set aside.

Step 2

Peel and quarter the celery root and julienne on a mandoline or with a sharp knife. Toss with one Tablespoon of the lemon juice in a large serving bowl and set aside.

Step 3

Core and cut the apple into quarters and julienne on a mandoline or with a sharp knife . Toss the apple with shaved celery root and the remaining Tablespoon of lemon juice and set aside.

Step 4

Thinly slice the celery stalks on a mandoline or with a sharp knife and toss with the celery root and apples.

Step 5

Toss with the finely chopped celery leaves, parsley leaves and mustard vinaigrette until well combined.

Step 6

Top with the toasted walnuts and an additional sprinkle of sea salt if desired before serving.