Wash apples, grate dry. Cut out the core with an apple core cutter. Cut apples into 8 slices. Heat 1 tablespoon of oil in a frying pan and fry the apple rings in 2 portions on each side for about 1 minute.
Drain on kitchen paper.
Peel the onion and cut into fine cubes. Wash the chives, shake dry and, except for a few stalks for garnishing, cut into fine rolls. Mix vinegar, mustard and sugar. Fold in oil in a thin stream.
Season to taste with salt and pepper. Stir in diced onion and chives.
Clean the salad, wash and spin dry. Cut smaller if necessary. Cut cheese slices in half horizontally. Cover a slice of pumpernickel with some salad, 2 apple slices and 2 half cheese slices.
Drizzle some dressing over it. Cover the remaining pumpernickel slices in the same way and garnish with chives.
Mix the remaining salad and dressing. Arrange in a bowl and serve with the Harzer breads.