Cut each scallop horizontally in half to make 2 coins.
Smash 6 slices ginger with flat side of knife. Cut 6 scallions crosswise in half and smash. Heat smashed ginger and scallions, the water, and 1/4 cup rice wine in large saucepan to boiling. Reduce heat to low and simmer 5 minutes.
Meanwhile, mince remaining slice ginger and scallion and mix with garlic in small bowl.
Mix broth, oyster and soy sauces, 1-1/2 T. rice wine, the cornstarch, sugar, and sesame oil in mixing bowl; set oyster sauce aside.
Add scallops to poaching liquid in saucepan and simmer until just cooked through, about 1-1/2 minutes. Drain scallops.
Heat wok or large skiller over high heat. Add 1 T. oil and heat until hot. Add snow peas, remaining 2 T. rice wine, and the salt; stir-fry until peas are tender but still bright green, about 2 minutes. Spoon peas around edge of large platter and spoon scallops in center.
Heat work over high heat, add remaining 2 T. oil and garlic mixture, and stir-fry 10 seconds. Stir in oyster sauce and cook until thickened. Pour sauce over scallops and serve at once.