Kohlrabi and Apple Salad with Creamy Mustard Dressing Recipe

1/2 cup heavy cream
2 tablespoons fresh lemon juice
1 tablespoon coarse-grained mustard
3 tablespoons finely chopped fresh parsley leaves
1/2 teaspoon sugar
2 bunches kohlrabi (about 2 pounds), bulbs peeled and cut into julienne strips, stems discarded, and the leaves reserved for another use
1 Granny Smith apple

In a bowl whisk the cream until it holds soft peaks and whisk in the lemon juice, the mustard, the parsley, the sugar, and salt and pepper to taste. Stir in the kohlrabi strips and the apple, peeled, cored, and diced, and combine the salad well.