Dab the meat dry and place it on a fat pan. In the preheated oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer) first roast for approx. 1 3⁄4 hours.
Peel and finely chop the onion. Wash the thyme and pluck the leaves from the stems. Mix both with jam and oil. Spread the roast with half of the spice paste and continue cooking for about 45 minutes. After about 20 minutes, spread the rest of the seasoning paste on top and finish cooking. Remove the roast, wrap in aluminium foil and let it rest.
Mix mustard and cranberries. Arrange roast. Serve with cranberry mustard.