To make the filling, heat the oil in a saucepan over medium heat. Add the onion, garlic and carrots, and sauté for five minutes until the onion is translucent. Set aside to cool. When cool, put the onion mixture in a bowl with all the pork meats, salt, pepper, spices, ground peppercorns and thyme and mix well. Add the stock, a 65ml cup at a time, until the liquid is incorporated. Cover and refrigerate.