How to Make It
In a large bowl, whisk the lemon juice with the salt, pepper and thyme. Gradually whisk in the olive oil.
In a large pot of boiling salted water, blanch the celery root until crisp-tender, about 1 minute; drain well and pat dry. Add the celery root to the lemon dressing and toss. Let cool slightly, then toss with the parsley. Transfer the salad to a bowl, crumble the feta on top and serve warm or at room temperature.