Place the pork butt into a large resealable plastic food storage bag. In a blender, combine the garlic, salt, white wine, vinegar, lemon juice, olive oil, paprika, red pepper flakes and bay leaf. Blend until smooth and pour over the pork. Seal the plastic bag and set in a casserole dish and place in the refrigerator over night.

Set a large braising pan or Dutch oven over medium-high heat. Add the olive oil and bacon fat to the pan. Remove the pork from the refrigerator and drain, reserving the marinade. Sear the pork pieces in the hot fat in batches, until golden brown, about 2 to 3 minutes. Turn to the other side and sear for an additional 2 minutes. Remove the pork from the pan and set aside on a platter while you finish searing the remainder of the pork.

Once all the pork is seared and has been removed from the pan, add the onions to the pan and cook, stirring occasionally, until the onions are translucent, about 3 to 4 minutes. Add the garlic to the pan and cook for 30 seconds. Sprinkle the flour into the pan and cook, stirring continuously, for 1 minute. Add the chicken stock, tomato paste, Piri Piri, salt and reserved marinade to the pan and stir to combine. Continue to stir until the mixture comes to a boil. Return the pork to the pan and when the liquid returns to a boil, cover with a lid and reduce the heat to low. Cook, stirring occasionally, until the meat is tender, about 1 1/2 hours. Add the tomatoes and clams to the pan, stir to combine and cover. Raise the heat to medium-high and cook until the clams open, stirring occasionally, about 8 to 10 minutes. Remove the lid, reduce the temperature to low, and sprinkle with the parsley. Discard any clams that do not open, and serve the dish with French fries or steamed white rice