Trim fat from pork. If necessary, cut roast to fit into a 3- to 4-quart crockery cooker.
In a small bowl combine oregano, ginger, and pepper. Rub spice mixture over entire surface of meat.
Spray a large unheated, nonstick skillet with nonstick coating. Preheat over medium heat. Add roast and brown on all sides.
Transfer meat to the crockery cooker; add onions.
In a bowl combine 1 cup of the orange juice (chill remaining orange juice), the sugar, grapefruit juice, steak sauce, and soy sauce. Pour over meat in the crockery cooker.
Cover and cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours.
Transfer roast to a serving platter; keep warm.
For sauce, measure pan juices into a glass measure. Skim off fat. Add additional orange juice, if necessary, to make 2-1/4 cups.
In a medium saucepan combine cornstarch, remaining 1/4 cup orange juice, and the reserved orange peel; stir in reserved pan juices. Cook and stir until thickened and bubbly.
Cook and stir for 2 minutes more. Pass sauce with meat. If desired, serve with noodles.