Preheat oven to 350 degrees. Pat pork loin dry with paper towels. In a bowl, combine 1 /3 cup flour, salt and pepper, then rub over entire surface of roast. Place in roasting pan, cover, and roast for 1 hour. Add 1 cup water, cover and continue to roast until meat is tender when tested with fork, or until thermometer inserted in center of pork registers 160 degrees, about 1 hour. Remove roast to heated platter and cover with foil to keep warm.
For the gravy, -lace roasting pan on burner over moderately high heat and scrape pan to loosen browned bits on bottom. If liquid has evaporated, add about 1 cup water. Bring to boil and add salt and pepper.
In a cup or small bowl, whisk 3/4 cup cold water and cup flour until smooth. Slowly pour flour mixture into broth, whisking vigorously to avoid forming lumps. Allow gravy to continue cooking for 2 to 3 minutes to eliminate flour taste. As the flour heats, it will thicken the gravy. If it's too thin, add make more flour and cold water mixture and slowly stir in. If it's too thick, thin with water. Taste and season gravy with salt and pepper.
Carve roast and serve with gravy on side. Makes 8 servings. Enjoy!