For the water dough, sift the flour and sugar together and rub in the shortening. Gradually add water until mixture comes together. Knead 3-4 minutes until smooth. For the oil dough, combine the ingredients and press into a ball. Cover both dough and set aside for 30 minutes; divide each into four equal portions.
Preheat oven at 190°C. On a lightly floured surface, flatten water dough and wrap it around oil dough to enclose. Roll out into a thin oval. Starting from the short end, roll it up like a Swiss roll; give the dough a quarter turn. Repeat the rolling process once, finally shaping the pastry into a rough rectangle. Do the same with the remaining dough.
Spread a quarter of the lotus seed paste on one half of each rectangle; fold the other half over. Brush with a little oil and sprinkle with sesame seeds. Bake for 15-20 minutes until puffed and golden (traditionally, this pastry is deep-fried). Serve cut into slices.