We borrowed some of the flavors from classic green bean casserole to create this simple, bright green bean side. The soy sauce in the vinaigrette boosts the natural umami of the mushrooms, and a mixture of chopped and sliced mushrooms makes the dish more visually and texturally interesting. The vinaigrette can be refrigerated up to a day in advance; bring to room temperature before using. The mushroom and shallot mixture can also be cooked ahead. To do so, after they're well browned, pour ¼ cup water into the pan and scrape up any browned bits; let cool, then refrigerate in an airtight container for up to a day. When ready to serve, in a 12-inch skillet over medium, heat the mushroom mixture, stirring occasionally, until hot, then stir in the blanched green beans (no additional water needed) and cook until warmed through. Dress the beans off heat as instructed in the recipe.