1. Combine the pepper and cardamom; rub over roast. In a gallon size Ziploc bag, combine the soy sauce, vinegar, tomato paste, paprika and garlic powder; add the roast. Seal bag and turn to coat; refrigerate overnight.
2. Drain and discard marinade. Place roast on a rack in a shallow roasting pan. Cover and bake at 350 degrees F for 2 to 2 3/4 hours until meat is tender. Let stand for 20 minutes before carving.
3. Meanwhile, make the gravy. Combine the drippings from the roasting pan and loosened bits into a sauce pan; skim fat. Combine cornstarch and cold water until smooth; gradually stir into the drippings. Bring to a boil; cook and stir for 2 minutes or until thickened.