Marinate the wild boar in the fridge for 24 hours in a good red wine with the chopped vegetables and herbs (carrots, celery, onion, bay leaves, and some juniper berries). Discard the marinade ingredients.
Heat a heavy bottomed pan and add some oil, the brown the wild boar pieces on all sides.
Once the meat is nicely browned, add a glass of wine to the pan, can reduce it by about half.
Then add the passata and some juniper berries and simmer on a very low heat for 2 to 3 hours or until the meat is very tender.