Pre-cook beef brisket in 5 1/2 liters of water in about 25 min. 1-2 times, each time after corn starch (maizena) of the pickle. Pour away the water 2x. Fill up with fresh water and add onions, peeled and chopped and 6 black peppercorns and do up to 1 3/4 hours, so that the meat has bite and does not fall apart, but is cooked.
Meanwhile, in a frying pan, lightly brown shallots in calf kidney fat and keep warm. Remove the meat with the onions from the clear soup, remove the peppercorns and turn the meat through the mincer, then keep warm.
Add the potatoes to the soup. If necessary, add water to cover the potatoes. Cook on a low heat until the soup is almost empty. Mash the potatoes to a pulp. Pour all prepared ingredients together in a large saucepan and add coarsely ground peppercorns, 1 dash of Angostura bitters and 1 dash of Worcestershire sauce for seasoning and stir everything together well.
Top labskaus with a fried egg and garnish with beetroot and pickled cucumbers.
* A C H T U N G ! * In no case use beetroot juice, corned beef, matjes or salted herring.