First make the meatballs: in a shallow dish, soak the slice of white bread in whole milk so the bread is completely covered and set aside.
In a fry pan over medium heat, heat the butter and fry the diced onions until tender. When the onions soften, sprinkle them with salt and continue to try them, taking care not to burn them. When fragrant and translucent, transfer them to a dish and set aside to cool.
In a large mixing bowl, combine the ground pork, ground beef, onions, milk-soaked bread, mashed anchovies, wholegrain mustard, Worcestershire sauce, lemon zest, fresh dill, salt and white pepper, and whisked egg, but don’t over-mix; you want loose rustic meatballs, not smooth tight balls. Test the flavour by cooking a teaspoon of the mince in a microwave or fry pan, then adjust the seasoning if needed.
Use a teaspoon to scoop out around 32 g of the ground meat mixture, checking the weight on digital kitchen scales to ensure they’re all the same weight and will cook evenly, then roll the mince mixture a few times between your hands to shape it into a meatball. Transfer the meatball to a tray and repeat until you’ve used up all the mixture. It should make around 24-25 meatballs.
To a large deep skillet (big enough to hold all meatballs) over high heat, add a litre of boiling water, a tablespoon of salt, the bay leaves, cloves and whole peppercorns, bring to a boil, turn the heat to low to simmer, then transfer the meatballs to the broth.
Cover the skillet and cook the meatballs for 15-20 minutes until just done, turning them every 5 minutes to ensure they’re cooked evenly. Test a meatball after 15 minutes. When done, use a slotted spoon to remove the meatballs and transfer them to a tray and set aside.
Next make the gravy: transfer the meatball broth from the skillet to a jug and set aside. Use a paper towel to wipe the skillet, return it to the stove, and over medium heat, melt 20g butter, add the diced onions, and fry them until soft, fragrant and translucent.
Use a handheld sifter to gradually sift the flour onto the buttery onions and, with the other hand, use a wooden spoon or spatula to constantly stir the flour into the buttery onions to combine well. Continue stirring until it’s a milky-coffee colour, then gradually pour the meatball broth, little by little, into the skillet, continually stirring, until you have a light gravy.
Add the capers, taste, add salt if needed, add half the fresh dill, stir to combine, then return the meatballs to the gravy and heat over medium until hot.
Distribute between plates, garnish with the rest of the fresh dill and cracked black pepper, and serve with parsley buttered potatoes, creamy mashed potatoes and/or a crisp garden salad, with dishes of gherkins and sour cream.