Trim excess fat from roast; cut in half to fit into slow cooker. In skillet brown meat in hot oil; drain. Place meat in slow cooker; add bean sprouts, mushrooms, water chestnuts, and green pepper.
Stir together jam, vinegar, soy sauce, garlic, salt, ginger, and pepper. Pour over meat and vegetables. Cover, cook on low heat setting for 8 to 10 hours. Remove meat and vegetables. Skim fat from cooking liquid.
Measure 2 cups of the liquid; reserve. Return meat and vegetables to slow cooker; cove to keep warm.
Drain oranges, reserving 1/4 cup of the syrup. In a saucepan blend reserved syrup slowly into cornstarch; stir in reserved cooking liquid. Cook and stir until thickened and bubbly. Stir in orange sections; heat through. Season to taste.
Place meat and vegetables on platter. Spoon some sauce over meat and vegetables; pass remaining sauce. Serve with rice.