Cut the pork neck into 1 cm thick slices, then into medium-thickness strips. Cut the onions into fine strips. Place the pork and onions in a large bowl.
Mix the spices into a rub.
Pour the oil and spice mixture over the meat and mix well. Refrigerate for at least 4 hours, preferably overnight.
Cut the mushrooms and peppers into small pieces. Set aside.
Heat a Dutch oven to medium-high. Sear the meat in portions, then remove and set aside.
Add the tomato paste and ajvar to the Dutch oven and roast for roughly 2 minutes. Pour in the Metaxa, stir well, and let reduce for roughly 5 minutes. Add the cream and crème fraîche, stir well, and bring to a boil. Stir in the mushrooms, peppers, and meat.
Transfer to the oven and cook at 170°C (340°F) to 200°C (390°F) for 30-45 minutes until the pork reaches an internal temperature of 63°C (145°F).
Optional: add roughly 250-300 g cheese to the mixture before transferring to the oven.