Wash the potatoes and cook for about 20 minutes. Quench, peel and let cool down.
Clean the leek, halve lengthwise, wash and cut into strips. Steam covered in little boiling salted water for about 1 minute until al dente. Quench, drain and let cool down.
Dice the gouda and turkey breast. Cut the potatoes into slices.
Dissolve the broth in 1⁄8 l hot water. Stir in 5 tablespoons of vinegar, salt and pepper. Fold in the oil. Mix leek, potatoes, cheese and turkey with the marinade. Let stand for at least 30 minutes.
Mix fig mustard, sour cream and mayonnaise. Season to taste with salt, pepper, approx. 2 tbsp. vinegar and a little sugar. Mix the sour cream with the salad and let it stand for at least 1 hour. Flavour again.