Clean, wash and cut the beans into pieces. Cook in boiling salted water for about 15 minutes. Drain. Wash and slice the tomatoes and place them on a plate. Clean, wash and quarter the mushrooms.
Peel the vegetable onion and cut into thin slices. Mix vinegar, mustard, salt and pepper and add the oil. Mix the beans, mushrooms and onion slices with the marinade and arrange on the tomatoes. A farmhouse bread tastes good with it
Bowl + mustard jar: