Preheat your oven to 350°F (175°C).
Use a sharp knife to score the skin of the pork roast in a crosshatch pattern. Be careful not to cut into the meat.
Rub the pork skin and meat with vegetable oil.
Season generously with salt, pepper, and ground allspice (if using), making sure to rub it into the scored skin and meat.
Place the pork roast on a rack in a roasting pan.
Add the water, onion, carrots, bay leaves, and thyme sprigs (if using) to the bottom of the pan.
Roast in the preheated oven for 1.5 to 2 hours, or until the internal temperature of the meat reaches 145°F (63°C) and the skin is crispy and golden brown.
If the skin isn’t as crispy as you’d like, increase the oven temperature to 425°F (220°C) and roast for an additional 15-20 minutes, watching closely to avoid burning.
Remove the pork roast from the oven and let it rest for 10-15 minutes before slicing.
Enjoy your meal!