Wash beans. Cut into 2-3cm long pieces. Put in boiling, salted water. Cook for about 15-20 minutes. Drain on a sieve.
In the meantime, dice the cheese, pickles, eggs, onions, cleaned bell peppers and tomatoes. Mix the finely chopped ingredients with the beans.
For the marinade, mix together yogurt, mayonnaise, canned milk and mustard well. Season to taste with vinegar, sugar and pepper. Pour over the salad. Let it steep in the fridge for 15 minutes.