Soak the rolls in cold water for about 10 minutes. In the meantime, finely chop 1 tablespoon of capers and 1 anchovy fillet. Wash the parsley, dab dry and chop finely except for a little to garnish.
Wash the lemon hot, dab dry and finely grate the peel. Peel and finely chop the onion. Squeeze the bread roll well. Mix minced meat, roll, egg, capers, anchovy, onion, half of the lemon peel and parsley.
Season with salt and pepper. Form about 8 medium-sized meatballs with moistened hands and let them simmer in boiling salt water for about 20 minutes. In the meantime peel, wash and halve the potatoes. Cook in boiling salted water for about 20 minutes.
Melt 40 g of fat in a pot, add flour and sweat on over low heat for about 5 minutes without colouring. Stir in milk and add approx. 1/4 litre of the beating broth. Let simmer for about 10 minutes at low heat, stirring occasionally.
Finely chop the remaining anchovy fillet. Add to the sauce with the remaining lemon zest and capers. Season to taste with salt and cayenne pepper. Add the meatballs from the stock to the simmering sauce and let them simmer for about 10 minutes.
Drain the potatoes and let them evaporate briefly. Add the remaining fat and parsley and toss through. Arrange Königsberger meatballs with potatoes and beetroot on plates and garnish with remaining parsley.