Bring 2 cups water to a boil in a medium saucepan. Pour over dried shiitake mushrooms and let soak for 10 minutes to rehydrate. Meanwhile:
*Trim stems of fresh shiitake mushrooms and thinly slice.
*Rinse scallions, cut off root end and thinly slice from white to green tips.
*Drain liquid from noodles and rinse under cold running water for 20 seconds.
*Pick leaves off mint and finely chop.

Place eggs in a small saucepan with enough cold water to just barely cover. Bring to a boil and immediately take off heat. Cover and let sit for 4 to 6 minutes, depending on how soft you want the yolk. Remove from pan and run under cold water. Set aside to cool. Move on to next steps while waiting.

Heat 2 tablespoon oil in the medium saucepan until shimmering. Sauté fresh shiitake mushrooms until just soft, 2 to 3 minutes. Add scallions and sauté until fragrant, about 1 minute.

Strain soaking liquid from dried shiitakes into medium saucepan, careful to not include the grit that has fallen to the bottom. Stir in two cups water and miso broth sauce and bring to a boil. Meanwhile:
*Mince rehydrated shiitakes.
*Peel eggs and slice in half.
Once broth is boiling, add rehydrated shiitakes and spinach and cook until just wilted, about 1 minute. Take off heat and add salt to taste.

Divide noodles and bean sprouts evenly between two bowls. Ladle mushrooms, spinach and broth into both bowls. Top with soft boiled eggs and drizzle sesame oil evenly between two bowls. Garnish with mint.