Dice the pancetta. Put it in a cast-iron or clay pot, and melt the fat over a low heat. In the meantime, finely chop the vegetables, put them in the pan and add a drizzle of extra virgin olive oil. Let them soften gently. When the vegetables are soft, add the ground beef, slightly increase the heat and brown the meat evenly. When the meat is browned and sizzling, add the wine, turn up the heat and let the alcohol evaporate.
If the meat and pancetta have released too much fat, remove it. Puree the San Marzano DOP tomatoes in a blender and add to the meat, season with salt and turn down the heat; simmer gently for at least 2 hours. Once cooked, add a glass of milk, mix well and turn off the heat.
Use the sauce for your favourite pasta.