In a heavy large enamel cast iron pot heat the olive oil, butter, and garlic over medium heat. Once the garlic is brown but not burned, remove and discard.
Add the onions and carrots and mix well. When the onions are translucent, add the meats (beef, veal, and pork) and separate well with the back of a wooden spoon. Add the tomato paste and mix well.
Cook the meats until all the liquid is evaporated.
Add the bay leaves, red wine, chopped porcini mushrooms, and half of the strained mushrooms liquid. Mix well.
Add the tomatoes, salt, pepper, and sugar. Mix well, lower the heat to simmer, cover, and cook for 1 hour to 1 ½ hours. Stir occasionally. Taste and adjust the salt and pepper to your liking. Add more wine if too dry. Cook uncovered for another 30 minutes.
Remove the bay leaves before serving.