Mix together the onion, jalapeno, spices, oil, and soy sauce.
Place the rib roast in a roasting pan, ribs down. Spread the onion and spice mixture across the layer of fat on the roast and let sit at room temperature for 1 hour. Preheat oven to 500 degrees . Roast beef in the center of the oven for 20 minutes. Decrease temperature to 350 degrees and continue roasting for 1 to 1 1/4 hours longer until a meat thermometer inserted into the center registers 135 degrees for medium rare. Let sit 20 minutes before slicing.