Marinade: In a large bowl combine the wine, brandy, onions, carrots, parsley, bay leaf, garlic, peppercorns and salt. Mix well then add the cubed beef. Cover and marinate in the refrigerator for up to 2 days.
Preheat oven to 150 degrees C.
Bourguignon: Strain the meat from the vegetables and marinade; reserve marinade. Dry meat with paper towels. Heat 2 tablespoons of the oil in a large frypan over medium high heat. Add the meat and saute for 10 minutes, or until browned on all sides. Transfer meat to a separate medium bowl with a slotted spoon and set aside.
In the same frypan, add the bacon and saute until lightly browned. Transfer the bacon to the bowl with the meat. Drain the frypan and return it to the heat. Pour a cup of marinade into the frypan to deglaze the frypan, scraping the bottom to loosen up all the little bits. Return this liquid to the reserved marinade.
Heat the remaining oil in the frypan. Add the onion and carrot from the marinade, along with the additional onion that you've diced then saute for 5 minutes or until tender. Transfer this mixture to the bowl with the meat and bacon, again using a slotted spoon, and return frypan to the heat. Add the flour to the frypan, combining with the oil and stir until well mixed and brown; about 2 minutes.
Now add the tomato paste, garlic, beef stock, reserved marinade, salt and pepper, to taste. Bring to a boil and whisk to remove any flour lumps. Add this to the meat and vegetable mixture. Place entire mixture into a baking dish.
Bake at 150 degrees C for 3 hours, stirring occasionally and adding water as needed. Season with salt and pepper to taste.
About 15 minutes before meat is done baking, melt butter in the frypan over medium high heat. Add the mushrooms and saute for 5 to 10 minutes, or until lightly browned. When meat is done, add the mushrooms to the meat mixture, stir well and let sit for about 15 minutes.