Remove roast from packaging, pat dry with a clean paper towel. Trim with knife as needed. Transfer to a sheet tray to season.
Mix together garlic paste, oil, mustard, salt and pepper in a bowl. Using a gloved hand, massage seasoning mixture into the meat only.
Place in your refrigerator overnight uncovered.
Before cooking, stand upright on a roasting rack lined sheet tray.
Heat oven to 450 degrees. Roast for 20 minutes, then turn heat to 350 degrees and continue to roast until the meat registers 115 degrees on an instant-read thermometer for rare, 125 for medium rare (it will continue to cook after you pull it out of the oven). Timing depends on your oven, your pan and the shape of your roast, so start checking after the meat has been in the oven for an hour, but it could take 1 1/2 hours or even slightly longer.
Let meat rest at room temperature for 20 minutes before carving.