Slow Cook:5 hrs to 6 hrs (low) or 2 1/2 to 3 hours (high)
Place turkey in a 3 1/2- or 4-quart slow cooker. Sprinkle with black pepper and cayenne pepper. In a small bowl, combine broth, soy sauce, ginger, lemon juice, sesame oil and garlic. Pour over turkey.
Cover and cook on low-heat setting for 5 to 6 hours or on high-heat setting for 2 1/2 to 3 hours.
Transfer turkey to a serving platter, reserving cooking liquid. Cover turkey and keep warm.
For sauce, strain cooking liquid into a small saucepan. In a small bowl, combine cornstarch and the water; stir into cooking liquid. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more.
If desired, slice turkey. Spoon sauce over turkey. Sprinkle with green onion and sesame seeds.