Combine 190 g medium-protein wheat flour, icing sugar, and salt in a mixing bowl; stir until evenly mixed.

Add 100 ml water to the dry mixture and stir until a rough dough forms; add 50 ml vegetable oil and knead until smooth.

Cover the dough with a kitchen towel; rest it for 30 minutes at room temperature.

Combine 65 g medium-protein wheat flour, 30 ml vegetable oil, and margarine in the second bowl; knead until smooth.

Divide the second dough into 20 equal portions; roll each portion into a small ball.

Briefly knead the rested first dough; divide it into 20 equal portions.

Flatten one first-dough portion with the rolling pin; place one second-dough ball in the center and seal it inside.

Roll the filled dough into a thin rectangle; fold the left and right sides inward, then roll it into a cylinder.

Repeat the layering process for all portions; submerge the dough cylinders in vegetable oil for 10 to 15 minutes.

Drain the dough cylinders from the oil; roll each one into a thin round wrapper.

Place about 25 g purple sweet potato paste in the center of each wrapper; gather the edges and seal each pastry.

Preheat a covered dry pan over low heat; arrange the pastries seam-side down in the pan.

Cover the pan and cook the pastries for about 8 minutes; turn them over carefully.

Cover the pan again and cook for about 8 minutes until both sides are cooked through; cool slightly before serving.