Combine cabbage and 1 tablespoon of salt; let sit for 30 minutes. Rinse and squeeze cabbage dry. Combine with pork, ginger, scallion, soy sauce, sherry, 1 teaspoon salt, and sugar in a large bowl.
Form 2 teaspoons of pork mixture into a ball and place on a baking sheet. Cover and refrigerate at least 30 minutes.
In a medium bowl, stir together flour, water, and 1/2 teaspoon salt with a fork. Knead dough until all flour is Incorporated.
Divide dough into three balls. Cover with plastic wrap and allow to rest for 30 minutes.
Roll out one ball of dough on a lightly floured surface until dough is 1/8 inch thick. Using a 3 1/2 inch round cutter, cut dough into 8 to 10 rounds. Cover rounds with plastic wrap. Repeat to roll and cut the remaining dough into rounds.
Shape dough circles around chilled pork mixture. To form a triangle fold place mixture into center of dough. Lightly pinch edges of dough to divide circumference of circle into thirds ( at 12 o’clock, 4 o’clock, and 8 o’clock positions.) Using your fingers, bring rounded edges of the dough together, encasing the filling and creating three equal sides. Use your fingers to firmly press the open rounded edges together to seal the dumpling. Place filled dumplings in a floured baking sheet.
In a saute pan over high heat, heat 1 tablespoon sesame oil. Place half the dumplings in pan. Reduce heat to medium.
Pan-fry dumplings 3 minutes. Slowly add 1/4 cup water, cover pan, and reduce heat to low. Steam for 6 minutes. Uncover pan, raise heat to medium-high, and cook until bottoms are crisp, 3 minutes. Repeat with remaining dumplings.