Take roast out of the refrigerator and let stand at room temperature for about 2 hours to take off the chill.
Preheat oven to 350 degrees.
Mash together the garlic, salt, pepper, oregano, and rosemary; rub seasonings into the roast.
Place meat fat side up on a rack in a shallow roasting pan.
Place meat in the oven and roast approximately 45 minutes, until lightly browned.
Open the oven and scatter the chopped vegetables in the pan around the roast.
Close the oven, then reduce temperature to 225 degrees.
Bake approximately 2 1/2 hours for rare (140 degrees on a meat thermometer), or longer for more well done.
When the meat is done to your satisfaction, take roast out of the oven and place it on a carving board to rest for about 10 minutes before carving.
Meanwhile, if enough juice has been rendered by the meat, prepare a natural gravy.
Remove excess fat from the pan and place pan over low heat.
Stir in a suitable amount of water (1 to 2 cups), scraping to deglaze the bottom of the pan.
Season with salt and pepper and a dash of Worcestershire sauce.
Reduce gravy slightly, strain, and check seasonings.