Soak the bread rolls. Peel and chop the onion. Knead both together with minced meat, squeezed out buns and egg and season. Form 8 meat loafs.
Heat the oil and fry the meat loafs for about 8 minutes on each side.
Clean the spring onion and cut it into pieces. Clean and chop the mushrooms, dice the bacon. In a wide saucepan, render the bacon and remove. Sauté the mushrooms and onions in the drippings, stirring constantly, and season.
Mix sauce powder and 1/4 l cold water. Deglaze the mushroom mixture with it.
Bring to a boil while stirring and simmer gently for about 1 minute.
Add the bacon. Season to taste with pepper and salt.
Serve the meatballs with the mushroom sauce.