In a medium bowl, combine cornstarch, sherry, gingerroot, sesame oil and salt. Add shrimp, tossing the mixture to coat the shrimp well. Let them marinate, covered and chilled, for 10 minutes.
In a large sauce pan, bring the cold water to a boil, add the shrimp, discarding the marinade, and return the water to a boil. Boil the shrimp for 1 1/2 minutes and drain them in a colander.
In a bowl , whisk together the broth, cornstarch, rice wine, soy sauce, sugar and salt. Set aside.
In a wok or large skillet, heat peanut oil over moderately high heat until hot but not smoking. Add garlic, scallions, bean sprouts, red pepper, bok choy and snow peas. Cook for 2 minutes. Stir in cornstarch broth, cook the mixture, stirring, for 2 to 3 minutes. Add shrimp and cook 1 more minute, until the vegetables are just softened and the sauce is thickened slightly.
Serve over rice or noodles.