You don`t necessarily need to prepare 2.5 kg of meat. Either do it with the Schäufele or with the Kasseler, if you prefer.
Wash, clean and roughly cut the vegetables. Put the Schäufele and the beer in a suitable saucepan. Add enough water to just cover the meat. Lift out again, bring the stock to the boil, add the meat again and let it simmer for 1.5 hours over a low heat. In the meantime, wash, cook and peel the potatoes.
Skim off about 1/4 liter of stock, stir with mustard, oil, vinegar, salt and pepper to a very spicy marinade. Cut the potatoes directly into it. Wash the chives, cut into rolls and fold in. Season again to taste, possibly add a little broth, the salad should be juicy.
Release the meat, cut into thin slices and serve with the salad