Dab meat dry and cut into 8 thin medallions. Wash the thyme and pluck the leaves from the stems.
Heat 1 tablespoon of oil in a frying pan. Fry the medallions for about 2 minutes on each side. Season with salt and pepper and sprinkle with thyme. Take them out and let them cool down. Put the pan with frying fat aside.
Soak gelatine in cold water. Place medallions in the freezer for about 10 minutes. Squeeze out the gelatine and dissolve in a saucepan over a mild heat. Stir in port wine. Remove medallions and cover with lukewarm port wine jelly.
Place in the refrigerator for another 15 minutes.
Salads clean, wash, shake well dry and pluck a little smaller. Peel and finely chop the onion. Heat 1-2 tablespoons of oil in the frying fat. Fry the onion in it. Stir in vinegar and cranberries. Season with salt and pepper.
Arrange salad and medallions. Drizzle with marinade.