Braised pork with quinces

2 1/2 lb (1.25 kg) boneless pork shoulder, trimmed of excess fat and cut into 2-inch (5-cm) cubes
2 teaspoons ground Cinnamon
2 teaspoons ground Cumin
Juice of 1 lemon
3 lb (1.5 kg) quinces
2 tablespoons unsalted Butter
1/2 cup (4 oz/125 g) Sugar
1 cup (8 fl oz/250 ml) pomegranate juice or water
1/4 cup (2 fl oz/60 ml) Olive oil
2 Onions, chopped
Pinch of ground cayenne Pepper, optional
1 cup (8 fl oz/250 ml) chicken stock or water
Salt and freshly ground black pepper

1. Rub the meat with 1 teaspoon each of the Cinnamon and cumin. Place the spice-coated meat in a nonaluminum bowl, cover and let marinate for 2 hours at room temperature or overnight in the refrigerator.
2. Fill a large bowl three-fourths full with water and add the lemon juice. Peel the quinces, core them and then slice thickly. As they are cut, drop them into the bowl of lemon water to prevent discoloring until all are cut.
3. Drain the quince slices and pat dry. In a sauté pan over high heat, melt the butter. Add the quinces and sauté until softened, about 10 minutes. Sprinkle with the Sugar and continue to sauté until golden, 15-20 minutes longer. Add the pomegranate juice or water and simmer over medium heat until tender, 15-20 minutes. Remove from the heat and let stand for 1 hour.
4. Return the quinces to a simmer over medium heat and simmer for 15 minutes longer. Remove from the heat and let stand for 1 hour longer; or let cool, cover and let stand overnight.
5. In a large, heavy sauté pan over medium heat, warm the olive oil. Add the pork and brown on all sides, about 10 minutes. Using a slotted spoon, transfer the pork to a plate and set aside.
6. To the fat remaining in the pan, add the onions. Sauté over medium heat until tender, about 8 minutes. Add the remaining 1 teaspoon each cinnamon and Cumin and the cayenne, if using. Sauté a few minutes longer to blend the flavors and then return the meat to the pan. Add the 1 cup (8 fl oz/250 ml) stock or water and stir well. Reduce the heat to low, cover and simmer for 1 hour.
7. Place the pan holding the quinces over medium heat and bring to a simmer. Simmer for 15 minutes. Add the quinces and their juices to the meat and continue to simmer over low heat until the meat is tender and the flavors have blended, about 30 minutes longer. Season to taste with Salt and pepper.
8. Spoon the stew into a warmed serving dish and serve hot.