In a large bowl, mix the celeriac with the salt and set aside for 10 minutes to allow the salt to soften the celeriac slightly.
Whilst the celeriac is softening you can make the dressing. In a separate, medium sized bowl, mix together all the ingredients for the dressing and whisk together until thoroughly combined.
Now add all the remaining ingredients for the salad to the bowl of celeriac and mix well.
Add the dressing to the salad and mix well.
Place the sliced lettuce into the base of a large serving platter or individual plates and top with the celeriac and apple salad. Garnish with the diced Saint Agur blue cheese and serve.