Finely chop onion, carrot, and celery.
Heat olive oil in a pan and sauté the chopped onion, carrot, and celery.
Add minced beef and pork, and cook until done.
Add tomato paste and minced garlic, and stir-fry.
Pour in white wine or red wine, and cook until the alcohol evaporates.
Add chopped tomatoes, bay leaf, salt, and pepper, then simmer on low heat.
Add a small amount of milk and simmer for over an hour to finish.