Pat dry the meat and season it with salt and pepper.
Heat 4 tablespoons olive oil in a brasier pot or dutch oven. Add the meat. Brown the meat over medium-high heat all over. If necessary do this in two batches so it doesn't get overcrowded in the pot. Then remove from the pot and set aside covered. Drop the heat to medium.
Add the tomato paste and 400 ml of red wine to the pot. Deglaze the bottom of the pot with a wooden spoon. Wait until the wine begins to boil.
Pour in the stock and add the rosemary, bay leaves, thyme, garlic cloves, allspice, and grape molasses.
Add the meat back to the pot along with its resting juices. Cover the pot and simmer over low heat for 40-50 minutes.
Meanwhile, prepare the quince. Peel the fruit and cut it into 3-4 cm (1⅓-inch) thick wedges.
Heat a non-stick frying pan over medium-high heat.
Saute the quince in 2 batches. Saute for at least 15 minutes for each batch until they get some color all over. Turn the fruit often using tongs so it won't burn. Set aside on a plate.
Add 1 tablespoon of olive oil and the pearl onions to the same pan. Saute for about 10 minutes to get some color all around.
Pour the remaining 50 ml of red wine into the frying pan and deglaze.
Pour 200 ml of hot water and cook turning the onions now and then, until the water evaporates and there's only a thin layer of glazy liquid left in the pan.
Transfer the contents of the frying pan into the pot with the meat. Shake the pot for the onions to submerge.
Lay the quince on top and put the lid back on.
Simmer covered for another 40 to 50 minutes. Or until the sauce is thickened.
Taste for any additional seasonings. Then turn the heat off and add the vinegar.
Allow the food to rest in the pot for 15 minutes before serving.