Step 1

Cook mushrooms and 1 teaspoon salt in a large, dry saucepan over medium heat, stirring occasionally, until mushrooms collapse, darken slightly, and most of moisture cooks out, 12 to 15 minutes.

Step 2

Add oil and chopped scallions; cook until scallions are tender, 2 to 3 minutes. Stir in ginger, garlic, and miso and cook just until fragrant, about 30 seconds. Add broth; bring to a boil. Reduce heat to low; simmer 5 minutes.

Step 3

Reserve 2 tablespoons coconut milk, then add the rest to a blender with mushroom mixture (work in two batches, if needed). Purée until very smooth, about 2 minutes, removing blender cap and covering hole with a folded kitchen towel to allow steam to escape.

Step 4

Return mixture to saucepan and bring to a simmer over medium heat. If a thinner soup is desired, stir in more broth, a little at a time. Season with salt and white pepper and serve, drizzled with remaining coconut milk and topped with fried mushrooms and scallion tops.