Peel and finely chop the onion. Knead minced meat, diced onion, breadcrumbs and mustard to a mass. Season with salt and pepper. Form approx. 4 dumplings from the minced meat mixture
Bring the stock and lemon juice to the boil in a wide pot. Add the meatballs to the stock, bring to the boil briefly, cover and cook over a low heat for about 15 minutes
Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. Remove the finished dumplings from the stock with a skimmer. Pour stock through a fine sieve and collect. Measure out 100 ml stock. Cut beetroot into slices
Melt butter for the sauce. Add flour and sweat for about 1 minute while stirring. Pour stock into the roux while stirring and bring to the boil. Let simmer for about 5 minutes. Add capers and cream, bring to the boil, season with salt and pepper. Add meatballs to the sauce and heat
Wash parsley, shake dry, pluck leaves from the stalks and chop finely. Drain the potatoes. Arrange potatoes, beetroot and dumplings on a plate and sprinkle with parsley