3 Tbsp unsalted butter
1 Tbsp olive oil
1 medium onion, chopped
1 carrot, chopped
1 stalk celery, chopped
1/4 pound pancetta or bacon, chopped
1 pound lean ground beef
1 cup dry white wine
salt and black pepper
1 28 ounce can peeled tomatoes, with juice

Melt the butter with the oil in a large, heavy skillet. Add the onion,
carrot, and celery and saute them briefly until colored.
Add the pancetta and ground beef, and cook the mixture over medium high
heat, stirring, until the beef loses its raw red color. Add the wine
and salt and pepper to taste, and cook the mixture until the wine
evaporates. Reduce the heat to low, stir in the tomatoes, and continue to cook
the
sauce gently for 2 hours, stirring occasionally.