Finely chop parsley and grate cheese on a coarse grater. Soak white bread in milk for 2 minutes, squeeze out excess milk. Combine minced meat, eggs, squeezed bread, cheese, parsley, salt, and pepper in a bowl. Mix thoroughly.
Wet your hands. Form meatballs roughly walnut-sized (about 3 cm). Set aside.
Peel and finely chop the 2 onions and 2-3 garlic cloves. Heat 4 tbsp vegetable oil in a deep frying pan over medium heat. Add onions and garlic, fry for 5 minutes, stirring occasionally.
Mix 1 liter water with 2 tbsp tomato paste and salt. Pour into the pan with onions and garlic. Bring to a boil over medium-high heat.
Place meatballs into boiling sauce. Reduce heat to low, cover, and simmer 40-50 minutes until sauce thickens and pork/beef reaches 63°C (145°F) internally. Serve with your favorite side dish.