The day before, mix yoghurt and 1 teaspoon of salt. Line a large sieve with kitchen paper and hang over a bowl. Pour in the yoghurt and let it drain well in the refrigerator overnight
Halve the slices of bread. If necessary, toast in a toaster or 1 tbsp. hot oil in a coated pan for 1-2 minutes on each side. Clean and wash the arugula. Cut approx. 1/4 finely and stir into the yoghurt. Season to taste
Clean, wash and slice the radishes. Peel kohlrabi and cut into thin sticks. Sort the sprouts, rinse. Peel and finely chop the onion. Mix with vinegar, salt and pepper. Whip 3 tbsp. oil into it. Mix radishes, kohlrabi, sprouts and the rest of the rocket with the marinade
Cut off approx. 8 balls or cams from the yoghurt with an ice-cream scoop or 2 tablespoons and place them on the bread. Sprinkle with pepper. Serve everything