1. Prepare the Pork: Place the butterflied pork on a clean work surface. If necessary, gently flatten thicker areas so the meat has an even thickness.
2. Make the Seasoning: In a bowl, combine garlic, onion, citrus juice, vegetable oil, salt, pepper, oregano, cumin, paprika, coriander, and parsley.
3. Season the Meat: Spread the seasoning mixture evenly over the inside surface of the pork. Cover and refrigerate for approximately 2 hours.
4. Roll the Pork: Roll the seasoned pork firmly into a compact log, keeping the filling inside. Secure it at regular intervals with kitchen-safe cooking twine.
5. Prepare for Roasting: Place the rolled pork seam-side down in a roasting pan. Preheat the oven to 180°C (350°F).
6. Roast: Roast for approximately 1 hour 30 minutes to 1 hour 45 minutes, depending on the thickness and cut. Use a food thermometer to check that the centre reaches a safe temperature. For pork roasts, the minimum is 63°C (145°F), followed by a 3-minute rest.
7. Rest the Meat: Remove the pork from the oven and let it rest for at least 10–15 minutes before removing the twine and slicing.
8. Serve: Cut into thick rounds and serve with roasted potatoes, fresh salad, or traditional Paraguayan side dishes.