This recipe can be doubled easily. Use a larger steamer, about ten inches in diameter, to cook all four portions at once in the same basket.
Stir ginger, orange zest and juice, coriander, oil, soy sauce, wine, and scallions in a medium bowl. Season with pepper. Add fish and mushrooms; turn to coat completely. Marinate 10 minutes.
Fill 2 woks or large pots with about 1 inch of water. Bring to a boil. Brush bottom baskets of two 6-inch, 2-tiered round bamboo steamers with oil. Place 1 fillet and 3 mushrooms in a single layer in each bottom basket; place half the edamame in each top. Cover baskets; carefully set into boiling water. Steam until fish is just cooked through, 10 to 14 minutes, checking occasionally to make sure water doesn't completely evaporate. Sprinkle edamame with salt. Serve in baskets.