Peel the onion. Clean and wash the leek. Cut both into fine rings. Boil up about 6 tablespoons of water, broth and vinegar. Steam leek and onion for about 2 minutes. Season to taste with mustard, salt and pepper. Let cool off
Cut the sausage into half slices. Clean and wash the lamb's lettuce. Mix both with corn, leek and onion with marinade. Season to taste. Add bread