Pre heat the oven to 220°C.
Sauté the onions, mushrooms and garlic in a little low calorie cooking spray, until they are soft.
Add the red wine vinegar and balsamic and allow to reduce until all the liquid has evaporated.
Remove from the heat and set aside.
Remove the sausage meat from the skins and place it in a large bowl, then add the minced beef and pork.
Add nutmeg, coriander, allspice and thyme, then season with a little salt and pepper (don't forget the bacon will be salty). Using your hands, mix well until everything is combined.
Mix in the onions, mushrooms and garlic, then add the beaten egg. Combine well with your hands.
Spray a roasting pan with low calorie cooking spray and place all the mixture in it, moulding it into an oval shape. Arrange the bacon medallions over the top, overlapping each piece and tucking the ends under the meat so that there are no gaps. Spray the surface with some low calorie cooking spray.
Tuck some bay leaves into the bacon, then cook in a preheated oven for 10 minutes. Then lower the heat to 180°C and cook for 1 hour and 15 minutes.