Remove stems from mushrooms. Reserve stems. Slice mushroom caps into (1/4-inch) julienne strips; set aside.
Combine stems, broth, ginger, and garlic in a large saucepan; bring to a boil. Reduce heat, and simmer 15 minutes. Strain broth through a sieve into a bowl; discard solids. Add miso to broth, stirring well with a whisk. Add tofu. Cover and keep warm.
Heat oil in a large nonstick skillet over medium-high heat. Add sliced mushrooms caps and pepper to pan; sauté 3 minutes or until browned. Add to broth mixture.
Cook noodles according to package directions, omitting salt and fat. Drain and rinse with cold water; drain.
Place 2/3 cup noodles into each of 6 shallow bowls; pour 1 1/2 cups hot broth mixture over each serving. Garnish each serving with 1/4 cup cabbage, about 1 1/2 tablespoons carrots, about 1 1/2 tablespoons onions, and 1 teaspoon sesame seeds.