Mix together all the ingredients for the dipping sauce and set aside.
Mix together all the ingredients for the pancake filling and set aside.
Whisk the egg white with half a cup of water until frothy. Mix in the flour and starch just until blended. Stir in the sesame oil.
Add the filling to the batter and fold in.
In a frying pan, heat enough cooking oil to reach a depth of a quarter inch.
Spread the pancake mixture on the hot oil and cook over medium-high heat until the underside is lightly browned and crisp.
Flip the pancake, drizzle in two to three tablespoons oil along the edges and partially lift the pancake edges to allow the oil to spread to the center of the pan.
Cook the pancake until the other side is browned and crisp.
Slide the pancake to a plate, cut into wedges or squares (kitchen shears will do the job well), garnish with sesame seeds and scallions, and serve with the dipping sauce.