The day before, peel and finely chop the garlic. Wash and chop the marjoram. Mix both with vinegar, mustard, sweet paprika, 1 tsp. pepper and oil. Rinse the meat, dab dry and coat all around with the prepared marinade. Wrap in cling film and keep cool overnight.
The next day peel and quarter the onions. Season the meat with salt and put it on a fat pan with the onions. Bake in the preheated oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer) for approx. 1 3⁄4 for 2 hours. Dissolve the stock in 1 l hot water, pour around the roast after approx. 45 minutes.
Remove the roast, wrap in aluminium foil and let it rest. Pour frying stock through a sieve into a pot and possibly fill up to approx. 1 l with water. Mix starch and 4 tablespoons of water. Bring the stock to the boil, stir in the mixed starch and simmer for approx. 3 minutes. Season sauce with salt and 1 pinch of sugar.