Peel and finely chop the onions. Finely chop the garlic as well, or press it through a garlic press.
Place the ground meat in a large bowl and mix with the chopped onions, garlic, eggs, and breadcrumbs. Add the mustard, paprika, and parsley, and season generously with salt and pepper.
Thoroughly knead everything with your hands until a smooth mixture is formed. Then shape it into an oblong meatloaf.
Heat the oil in a large frying pan or roasting pan. Carefully place the meatloaf in the pan and sear it thoroughly on all sides until it has a nice brown crust.
Preheat the oven to 180°C (350°F) using conventional oven settings (top and bottom heat). Then place the meatloaf in a casserole dish or roasting pan and cook for approximately 45–55 minutes.
Meanwhile, prepare the sauce. Slice the extra onion into thin rings and sauté slowly in butter or oil over medium heat until soft and golden brown. Add the tomato paste and sauté briefly.
Sprinkle the flour over the top and stir well. Gradually pour in the stock, stirring constantly to prevent lumps from forming. Let the sauce simmer gently for a few minutes until it thickens slightly. Season with salt and pepper.
Remove the cooked meatloaf from the oven and let it rest for about 5-10 minutes before slicing. This will keep it juicier when sliced and prevent it from falling apart.
Cut into thick slices, add the braised onions and some sauce, and serve immediately.
The onion meatloaf tastes especially delicious with creamy mashed potatoes and vegetables. It also reheats perfectly the next day.
