Rinse the wild boar and place it in a bowl that fits it comfortably. Add the chopped carrots and celery, the quartered onion, the bay leaves, rosemary, garlic and juniper berries. Pour in the red wine to completely cover the meat, close the bowl with clingfilm and put it in the fridge to marinate overnight.
The next day remove the bowl from the fridge and bring the meat back to room temperature. Cut the wild boar into regular pieces slightly bigger than a walnut, then put it aside.
Filter the marinade and collect it in a jug, you will need you later.
Finely chop all the vegetables, rosemary and juniper berries, leaving the bay leaves whole.
Pour the olive oil into a thick bottomed pot and add the chopped vegetables and the bay leaves. Let it brown on low heat for about ten minutes until it softens. Now add the wild boar and stir well to mix it with the sautéed vegetables. Season the wild boar with two generous pinches of salt and a few turns of black pepper. Cook it over medium heat for about ten minutes until seared.
Pour in the wild boar marinade, then move it on low flame and cover the pot with a lid.
Braise the wild boar for about two and a half hours, checking it from time to time to prevent it from drying too much. After about one hour add 500 ml of slightly salted hot water.
When the wild boar is almost ready, add the olives and cook for the last five minutes.
Turn off the heat and let it rest for a few hours. It will gain flavor.