Toast the glutinous rice flour in an oven (conventional or toaster is fine) at 350F for 8 minutes (it won’t get golden; this is to get rid of the raw taste). Let cool slightly.
Combine all of the filling ingredients in a bowl and mix until sticky and a paste like mixture forms. Set aside.
Pastry
Combine the flour, sugar and salt until completely combined. Add the oil and ice water, then mix until a dough forms. Mix/knead/press the dough for another minute to make sure that the dough develops a little more gluten to hold together later. Don’t worry if there are white streaks in the dough.
Assembly
Divide the dough into 20 equal portions, and do the same with the filling.
Working with one piece of dough at a time, roll the dough into a ball, then flatten it using your palms. Place a portion of the filling in the center, then wrap the dough around the filling until the filling is completely sealed inside the dough.
Don’t worry if there are a few cracks here and there; patch them up as best you can, then keep going. The filling won’t seep out during baking, I promise.
Place the cake on a parchment lined baking sheet, then repeat with the rest of the dough and filling.
You can place the cakes pretty close together, since they don’t spread much.
Press the cakes down slightly with your palm, then use a sharp knife to cut two slits in the top of the cake. Brush with the egg wash and sprinkle with sesame seeds.
Bake the cakes at 375F for 25-30 minutes, or until lightly golden. Let cool before eating.
Recipe Notes
You can find candied wintermelon at traditional Chinese medicine and herbal shops, or at little mom and pop Chinese grocery stores. Keep in mind that it’s a seasonal ingredient typically only sold around Lunar New Year time (plus or minus a month), so you can alternatively try looking online or candying your own wintermelon if you can’t find any pre-made candied wintermelon.
Store them at room temperature for up to a couple days, or in the freezer for up to a couple of months.