Start making the soffritto by finely chopping the onion, carrot and celery or if you don't want chunks in the sauce, you can use a mixer until they're finely shredded.
Add 2-3 tbsp of EVO oil in a large pot and add the soffritto. Turn on the medium heat and cook until they become really soft (do not brown).
Add the ground meat and the sausages and turn the heat to high and cook until the meat changes color, then add salt and pepper to season the meat. Finally pour the wine and let evaporate the alcohol.
Purèe the San Marzano tomatoes in a blender, then turn the heat to low and add the pureed tomatoes to the pot. Add enough beef stock to cover all. Add also the concetrated tomato paste and mix.
Taste and season accordingly; if necessary, add some sugar to break the acidity of the tomatoes.
Finally, add the bay leaves and the juniper berrier. Mix well with a wooden spoon and cover the pot with the lid. Let it simmer for at least 2 hours stirring every once in a while. If the sauce reduces too much, add some more beef stock.