Lower the heat and add 1 tablespoon olive oil, chopped onions, 1 teaspoon habanero sauté for 3 minutes, add the chopped garlic, sauté for 2 more minutes. Add the carrots, celery and sauté until they begin to soften, about 5 minutes. Add the sherry and deglaze the pan, scraping up any browned bits from the bottom of the pan. Add the bay leaves, sage, and the halved garlic head. Add the stock and bring it to a simmer. Return the pork to the pot. Crumble and wet a piece of parchment paper and place directly on top of the braise. Cover the pot with a tight fitting lid and place in the oven. Cook until the pork is tender, about 4 hours.