Place the red onions with the vinegar, red wine, brown sugar, cinnamon, cloves and allspice in a coated pan (wrap the spices in a cheesecloth, or in a tea egg so that they can be easily removed after cooking).
Bring the mixture to a boil and then simmer at low heat until it has a viscous, marmalade-like consistency. Let it cool down.
Roast peppercorns whole in a frying pan without fat until they burst open and give off a strong aroma, let them cool and coarsely grind them with a rolling pin or the bottom of a heavy pan.
Rub the steaks evenly with a little olive oil and Worcester sauce. Then roll the steaks in the ground pepper. Cook steaks on the grill until the desired level of doneness, remove from the grill and let rest for 3 - 5 minutes. Serve steaks with red onion marmalade.
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