Combine the boar cubes, red wine, juniper berries, bay leaves, and rosemary in a 3-quart / 2.8 L non-reactive bowl. Cover and refrigerate for 2 hours, stirring once halfway through.

Set a sieve over a bowl and drain the boar, keeping the wine, bay leaves, and rosemary and discarding the juniper berries. Spread the cubes on paper towels and pat them completely dry, then season with 1 tsp of the salt and the black pepper.

Set a rack in the lower third of the oven and heat it to 150 C / 300 F. Heat 1 tbsp of the oil in a 28 cm / 11-inch Dutch oven over medium-high heat until it shimmers. Brown half the boar for 5 to 6 minutes, turning, until deep brown on most sides, then move it to a plate. Add 1 more tbsp oil and brown the second batch the same way.

Lower the heat to medium and add the remaining 2 tbsp oil, the onion, carrot, celery, and the remaining 1/2 tsp salt. Cook for 8 minutes, scraping up the browned bits, until the vegetables are soft and pale gold. Stir in the garlic and tomato paste and cook for 2 minutes until the paste darkens to brick red.

Pour in the reserved wine, then add the bay leaves and rosemary. Simmer for about 6 minutes until the wine smells mellow and has reduced by about one third.

Stir in the crushed tomatoes, hot water, and the browned boar with any juices from the plate. Bring to a gentle simmer, cover, and transfer to the oven. Braise for 105 minutes, stirring once at the 1-hour mark.

Remove the lid and braise for 15 minutes more, until the sauce coats the back of a spoon and a cube shreds under a fork with no spring. Fish out the bay leaves and rosemary stems, stir in the parsley, and taste for salt.