Put noodles in a bowl with hot water, cover and set aside for 20 minutes.
Heat 2tsp oil in a saucepan, add scallion whites, mushrooms and carrot and cook over medium-high heat, stirring frequently, until mushrooms begin to soften, for about 2 minutes.
Add 5 cups of water and bring to a boil. Add edamame and cook for 4 minutes.
Drain noodles, and add to the pot along with spinach and ginger. Reduce heat to medium-low, and cook until edamame are tender. Stir in scallion greens.
Whisk 4tbsp miso into 1 cup of warm water.
Reduce heat to low, and stir in miso into soup. Add more miso for a more intense flavor, if desired. Season with salt and pepper.
Add sesame oil and tamari to taste. Serve hot. I served it with broiled eggplants.