Cook the pasta in 4-5 l boiling salted water (approx. 1 teaspoon salt per litre) according to the instructions on the packet. Peel and finely chop the onion. Heat 2 tbsp. oil and sauté onion in it. Deglaze with 2 tbsp vinegar and 100 ml water with broth.
Drain the pasta and rinse with cold water, drain. Put them back into the pot and mix with the hot marinade. Let it cool down.
In the meantime, remove the sausage from the skin, cut it in half lengthwise and cut into thin slices. Drain the cucumbers and collect the cucumber water. Cut cheese and cucumber into fine strips.
Wash herbs, shake dry. Chop parsley finely and cut chives into small rolls. Mix cucumber water, 4 tbsp vinegar, mustard, 1 tsp salt, some pepper and 1 tbsp sugar. Fold in 6 tablespoons of oil.
Mix pasta, sausage, cheese, cucumber, vinaigrette and herbs. Leave to stand for about 1 hour.
Clean, wash and drain the radishes and cut into thin slices. Wash and halve the tomatoes. Cut cress from the bed. Fold into the pasta salad with the tomatoes and radishes. Season salad with salt, pepper and sugar.