Peel potatoes and halve the big ones, if necessary, so that all are roughly equal-sized. Steam or cook in salted water for approx. 15 – 20 min. (depending on size of the potatoes) until they are cooked but still firm to the bite. (Potatoes that are too soft will turn your potato salad into mash). Meanwhile, boil the eggs for approx. 10 min. until hard. Set potatoes and eggs aside to cool down.
Finely dice pickles (best use small ones like cornichons) and apples. Chop chives. Mix mayonnaise, crème fraîche, mustard, pickle juice, lemon juice, salt, and pepper and set aside.
Peel and finely dice cold eggs. Cut potatoes in large chunks (to preference). Put them in a large bowl, together with the pickles and apple pieces.
Carefully fold in mayonnaise mixture, meat salad, and chives. (German meat salad is a sandwich spread that consists of mayonnaise, pickles, and mortadella. If you cannot buy it where you are, just use some extra mayonnaise and crème fraîche instead). Rest for at least 30 min. (I normally let it rest for half a day in the fridge). Season to taste before serving.