Mix all spices and oil together. If needed, add more oil to produce a thick molasses-like consistency. Rub mixture on roast and place in roasting pan. Cover with foil and bake approximately 30 mins per pound until internal temperature is at least 165f.
About an hour before it's finished, add a little water to the bottom of the pan and add lightly seasoned (salt/pepper/oregano), cut potatoes and carrots or green beans. Do not cover the vegetables with the water. Do recover the roast with foil to avoid drying it out.