1. Preheat oven to 425° F. Place the pork in a roasting pan. Cut several small slits in the pork around the top and sides. In a small bowl, combine the salt, sage, pepper, mustard powder and garlic powder. Stir in the oil to make a paste. Rub the mixture over the top and sides of the pork. Add the broth and cider to the bottom of the pan.
2.  Place the pork in the oven, and cook for 40 minutes. Reduce oven temperature to 325° F, and cover with foil. Cook for 1 hour 30 minutes. Remove foil. Continue to cook for another 1 to 2 hours or until an instant-read meat thermometer reads an internal temperature of 180° F. For additional browning, turn the oven to broil for 3 to 5 minutes. Watch closely for desired color. 
3.  Remove from oven, and transfer pork to a platter. Cover with foil. Let the meat rest for 30 to 40 minutes. Pour the liquid from the roasting pan into a saucepan, and bring to a boil. Sprinkle in the flour while whisking vigorously. Simmer for 10 minutes until gravy begins to thicken. Taste for seasoning, adjusting if necessary. Pour the gravy in a 2-cup measuring cup, and let cool in the refrigerator. Skim off any fat that develops as the gravy cools.
4.  Slice the pork. Spoon some of the gravy over the top, and serve additional gravy at the table.

Per Serving (2/3 lb): 

Calories: 600, Fat: 30 g (10 g Saturated Fat), Cholesterol: 235 mg, Sodium: 1,030 mg, Carbohydrates: 3 g, Fiber: 0 g, Protein: 81 g.