In a small bowl, combine the broth, soy sauce, cornstarch, gingerroot, peanut butter and pepper; mix until the cornstarch is dissolved. Set aside.
In a large nonstick skillet, heat the oil. Add the steak and cook, stirring frequently, until the beef is no longer pink and browned, 3 to 4 minutes. With a slotted spoon, remove the beef from the skillet and set aside.
Add the snow peas, scallions and sesame seeds to the skillet; stir fry until the vegetables are crisp-tender, 2 to 3 minutes. Return the beef to the skillet. Stir in the broth mixture, and cook until the meat and vegetables are hot and the sauce has thickened, 1 to 2 minutes. Cut open the hot potatoes and top them with the beef-vegetable mixture.