Preheat the oven to 350 degrees F. Trim any excess fat from the roast. In a bowl, mix together the salt, dry mustard, garlic powder, and black pepper. Sprinkle the roast evenly on all sides with the mixture, patting it so it sticks to the roast. Heat a thin layer of oil in a skillet over high heat. Add the roast and sear for 2 minutes per side until it is browned on all sides. Remove the roast from the skillet and place in a roasting pan. In a measuring cup, whisk together the ketchup, Worcestershire sauce, and broth. Evenly pour over the roast. Place the roasting pan in the oven and cook, uncovered, for 1 hour at 350 degrees F or until the meat is very tender. Remove the roast from the oven and cover loosely with foil. Let sit for 5 minutes before slicing.