Cut the onions into crescents. Rub the washed and dried meat with the prepared mixture; you can poke holes in it in several places for the spices to seep in deeper.
Put the seasoned meat in a baking bag, add the oil, wine, allspice and chopped onions inside. Close the bag well and leave the closed opening pointing up.
Bake in a preheated 428°F (220 °C) oven for 15 min., then lower to 338°F (170 °C) and bake for about another 80 min.