Celeriac, kohlrabi and apple remoulade

Method

1. For the mayonnaise, put the egg yolks into a mixing bowl and mix in the vinegar and ½ tsp salt. Then, using an electric hand whisk, very slowly trickle in the oil, whisking all the time, until you have a smooth, very thick mixture. This will make a little bit more than you need for this recipe but it’s difficult to make in small amounts and will keep in the fridge, covered, for a week.
2. For the remoulade, peel the thick skin off the kohlrabi, cut it in half, and shred into long thin strands on a mandoline. If you don’t have one, slice each piece across into 2-3mm thick slices, then cut each slice into matchstick-thin strands. Peel the celeriac, cut into quarters, then shred immediately, before it has time to turn brown. You should be left with about 500g shredded veg.
3. Spoon 200g mayonnaise into a mixing bowl, then stir in the mustard, vinegar, capers and cornichons. Season with salt to taste. Peel the apple and shred it on a mandoline or grater, giving it a one-quarter turn as soon as you get down to the core. Stir the grated kohlrabi into the mayonnaise mixture to help loosen it slightly, then stir in the celeriac, apple and chopped parsley. Serve straightaway.