1. Peel and seed kabocha squash. Cut squash into 1/4-in.-thick slices, each about 2 in. long and 1 in. wide, to make about 2 cups. Arrange kabocha in an even double layer in a 9- to 10-in. heat-resistant glass pie pan.
2. Sprinkle squash evenly with half the ginger and chile slivers. In a small bowl, mix Shaoxing rice wine, fish sauce,1 tbsp. soy sauce, and sugar. Drizzle half the wine mixture over squash.
3. Pour 1 to 3 in. water into bottom of steamer (see "Steaming Setups," below). Place rack at least 1 in. above surface of water. Cover and bring to a boil over high heat. Set pie pan on rack. Cover and steam until squash in center is tender when pierced, 9 to 12 minutes.
4. Meanwhile, rinse scallops, pat dry, and cut horizontally into 1/2-in.-thick slices. Mix scallops with remaining wine mixture.
5. When squash is tender, use tongs to arrange scallops in a single layer in center of pie pan, overlapping scallops if necessary but leaving squash exposed around edges. (Be careful of hot steam; remove rack or pie pan from steam with tongs and set it on a work surface if it makes arranging the scallops easier.) Cover and continue steaming until scallops are opaque on edges but still look transparent in centers, 2 to 3 minutes (they will continue to cook off heat; see Notes).
6. Turn off heat. Carefully lift pie pan from steamer. If it's difficult to remove, slip a wide spatula under pie pan to lift up, then grasp pie pan with a pot holder (or use two sets of tongs). Drizzle scallops with remaining 1 tbsp. soy sauce. Sprinkle with cilantro and remaining ginger and chiles.
Steaming Setups. All you need is a vessel to hold water, a rack to suspend the food over the water, and a lid to keep the steam in. Here are some possible combinations.
Wok and rack: A 14- to 16-in. wok with a domed lid and steamer rack or a round cake rack. Set wok on a ring if it wobbles. Put rack right in wok; the sloped sides will hold the rack over the water. The wide opening makes it relatively easy to remove the cooked dish. Woks run from $15 to $150 or more, and are widely available.
Bamboo steamer: Chinese stackable bamboo steamer baskets with lids. Set a 10- to 12-in. basket right in a 14- to 16-in. wok (make sure the bottom rim is just covered by water, as the baskets scorch easily; add boiling water as needed). Layer baskets to cook more than one dish. Bamboo steamers are generally $15 to $20 and are widely available.
Metal steamer: Chinese steamer pan topped with stackable baskets and a domed lid. Choose a 10- to 12-in.-wide steamer for greatest versatility. Stackable baskets can cook several dishes at a time. Metal steamers cost from $30 to $35 and may be found at Asian markets.
Western-style: A deep, wide pan or kettle with a lid, a round cake rack, and 3 empty cans. Set 2- to 3-in.-tall cans (both ends removed) into pan (or use the removable rim of a cheesecake pan). Top with a round cake rack and place pie pan on it; cover to steam.
Note: Nutrition analysis is per serving.