4 teaspoons vegetable oil, divided
⅓ lb shiitake mushrooms, stems removed
4 bunch scallions, sliced, white and green parts separated
1 3/4-inch piece fresh ginger, peeled and finely chopped 3 cloves garlic, chopped
6 cups vegetable broth
2 tablespoons white miso
1 tablespoon plus 1 tsp. tamari or soy sauce
2 teaspoons toasted sesame oil
4 large eggs
12 oz. fresh ramen noodles or 4 3-oz. packets dry ramen 2 heads baby bok choy, quartered lengthwise
2 teaspoons toasted sesame seeds
2 teaspoons crushed red pepper flakes
Toasted nori, for garnish (optional)