Apparently it’s pretty complicated. You have to make two different doughs and then press and roll them together before final assembly of the ball.
For the water dough:
1 1/2 cups all-purpose flour
2 tablespoons sugar
1/3 to 1/2 cup cold water
1 egg, beaten
20 grams lard
For the lard dough:
1 cup plus 2 tablepsoons all-purpose flour
100 grams lard
For the water dough, mix all of the ingredients together and knead until very smooth. Add water or flour as needed. The dough should be soft with no lumps. Divide into 12 balls. Set on table, cover with cling wrap, and let rest for 30 minutes.
For the lard dough, mix all of the ingredients together until they form a dough. Divide into 12 balls. Cover in cling wrap and set it aside.
Once the water dough has rested for 30 minutes, use your palm to press a ball of the dough into a round circle.
Add a ball of lard dough right into the center. Bring up the sides of the water dough and press flat.
Roll the hybrid ball of dough into a long, thin oval. Then roll it into a log, widthwise.
Repeat with the remaining 11 balls of dough, making sure to keep the finished logs under cling wrap to prevent drying out. Let the logs rest for 20 minutes.