Mix all spices together in a small bowl.
Rub spices over all sides of the roast.
Put roast in a roasting dish or a pan that can be covered in foil.
Put the lid on the roaster or cover the pan with tin foil.
Make sure the foil is snug against the pan and there are no places where the steam can leak out.
Place in a 250° oven and cook for 1 hour.
Lower the temperature to 170° and cook overnight.
The roast is ready to serve, the next day, at 1:00 pm.
If you want to serve later in the day, turn the oven off and keep the roast in the warm oven until you are ready to serve it.