Place the spring onion, ginger and mushrooms in a mixing bowl.
Mix the marinade with the garnish.
Boil the broth over medium heat for 15 minutes.
Fill a saucepan three-quarters full with hot water and bring to a boil. Once boiling, add the noodles and blanch them for 1 ½ minutes and fish them with tongs and drain.
Boil the wontons (usually 5-6 wontons per serving) in the same water for 3-4 minutes over medium heat. Remove the wontons then return the water or soup to a boil.
Before serving, soak the noodles in the broth for 30 seconds, then serve in a bowl.
Place the hot wontons on the noodles, pour 1 ladle of broth over the noodles and wontons.
Spread 2 teaspoons of tobiko or salmon roe over the wontons and add the filling.
A tip for folding the wonton: place the dough diagonally towards you and add 1 teaspoon of filling in the center. Lightly dip your fingertip into a bowl of water and run the tip over the edges of the dough. Overlap the edges to form a triangle, then scoop the dough and bring the sides together to form a fan-shaped money bag shape. Repeat until all of the batter or filling has been used.