Halve the matjes fillets lengthways and cut diagonally into bite-sized pieces. Cut the beetroot first into slices and then into small cubes. Peel and quarter the apple, remove the core and cut into small cubes. Peel and quarter the onion and cut into fine strips. Finely dice the pickles. Finely chop the dill. All ingredients (matjes fillet, diced beetroot, diced apple, onion strips, diced cucumber, 150 g Greek yogurt, 1 tbsp light rice vinegar, 1 tbsp pickled green pepper, 1 tsp sugar, 2 big pinches of coarse sea salt from the mill, 2 big pinches of colored pepper the grinder and 2 tablespoons of finely chopped dill) in a bowl and mix well. Place in the refrigerator until ready to serve.