Peel the kohlrabi, cut in half and slice thinly. Core the apples and slice to the same thickness. Peel the beetroot and grate coarsely on a cheese grater or shred on a mandolin. Mix together all the vegetables in a large bowl, then add the rest of the ingredients. Stir well, taste and season - you can afford to be generous with the salt. Pile up on a serving plate and garnish with extra chopped coriander.