For the homemade broth, bring the water to a boil, then add in the minced garlic, fennel seeds, juniper berries, bay leaves, peppercorns, and thyme. Let everything simmer for 10 minutes, then take the broth off of the heat and let it cool down to room temperature. Score the pork belly on the fatty side in a lattice pattern. Place the pork belly in the homemade broth and let it marinate for 24 hours in the refrigerator. For the pickled red onions, slice the onions, place them in a jar, and submerge them in vinegar. Seal the jar shut and transfer it to the refrigerator.
For the gnocchi dough, peel and cook the potatoes until tender, drain them, and mash them with a potato ricer or masher. Stir in the flour, semolina flour, egg yolks, salt & pepper until combined. Let the dough rest for 1 hour, then transfer it to a piping bag. Preheat the oven to 350°F and mix together the spices for the seasoning blend. Remove the pork belly from the broth and dry off both sides. Lay the pork belly on your work surface with the fatty side facing down, sprinkle with sea salt and the seasoning blend, and massage the seasoning blend into the meat.
Cover the surface of pork belly with ground beef, pushing it down firmly so that it stays in place. Remove the pickled red onions from the fridge and layer them on top of the ground beef. Pipe a thick strip of gnocchi dough down the center of the pork belly.
Press the two ends of the pork belly together and transfer it to a baking pan. Secure the ends together using a trussing needle and cooking twine. Place a baking rack over a baking tray. Once the ends of the pork belly are secured together, remove the porchetta from the baking pan and flip it over onto the baking rack so that the sewn side is facing down. Transfer the baking tray to the oven and bake the porchetta at 350°F for 4 hours.
