In a large heavy bottomed sauce pan, add the oil and bacon. Heat for 5 minutes, or until the bacon has rendered its fat, but not yet crispy.
Meanwhile, place the onions, celery, carrots and garlic into a food processor and puree until the vegetables are well pureed like.
Turn the heat to high and add the vegetables to the sauce pan. Cook for about 10-15 minutes, or until the liquid has been absorbed and the vegetables start to brown and stick to the bottom of the pan. Stir frequently.
Add the ground beef, ground pork and salt to the vegetable mixture. Stir well to incorporate. Cook for 10-15 minutes, or until the meat begins to stick and brown to the bottom of the pan.
Reduce the heat to medium. Add the tomato paste. Stir well and frequently. Cook for 2-3 minutes. Add the wine and scrape up the brown bits stuck to the bottom of the pan. Reduce the heat to medium low. Add the milk and thyme. Stir well. Bring to a simmer and cook for 1 hour. Stir occasionally, adding a touch of water to the sauce if it begins to look too thick.
Salt to taste and serve warm with cooked pasta.