Dutch Celeriac Salad (remoulade)

Preheat oven to 160°C.
Peel and cut the celeriac in very thin matchsticks using a mandolin. If you don’t have a mandolin you can thinly slice by hand, then lay flat on a board and cut into thin matchsticks. Only if you have slightly thicker matchsticks, pour some hot water over the cut celeriac, and leave for 1-2 minutes to tenderise. Drain well, pat dry with paper towel.
Place cut celeriac in a bowl, add lemon juice to keep the celeriac white and to help tenderise.
In another bowl, stir together the mayonnaise, Dijon mustard, and walnut oil, add to the celeriac and toss to combine.
Place the walnuts on a baking tray and roast for 10 mins or until golden. Cool, then roughly chop. Scatter over the salad and serve immediately with some smoked mackerel or on thinly cut bread, brushed with oil and roasted in the oven until crisp as a starter.