In a bowl, mix together all the ingredients except the dumpling wrappers, egg and cooking oil. Cover and marinate in the fridge overnight.
Take three dumpling wrappers and lay them side by side slightly overlapping each other.
Take three teaspoonfuls of the filling and spread across the wrappers near the center. Flatten the filling lightly with your fingertips.
Fold over the wrappers to enclose the filling. Press to flatten some more but DO NOT press the edges of the wrappers together. Leave them open.
Brush egg wash on the bottom of the dumpling from one end to the other.
Starting with one end, roll the dumpling all the way.
Repeat until all the dumpling wrappers have been filled and rolled.
Heat the cooking oil in a wide frying pan.
Arrange the dumplings, bottom side down, in the hot oil. Make sure that they do not touch to prevent them from sticking to each other. Fry the dumplings until the bottoms are lightly browned.
Pour in boiling water to a depth of half an inch.
Set the heat to low and cover the pan tightly. Let the dumplings cook in the steam for 15 to 20 minutes. Resist the urge to peek. Removing the cover of the pan to see how the dumplings are doing will result in loss of steam. Leave them be and let the steam do its work. By the time the water has dried up, the dumplings should be cooked through.
To serve, arrange three to four dumplings on a plate. Drizzle with a little soy sauce and sesame seed oil. Sprinkle with finely sliced scallions. Serve the rose dumplings hot.