Heat up a wok with 1 tablespoon of oil and stir-fry the dried shrimps until fragrant.

Transfer to a bowl.

Add in the ground pork, soy sauce, black pepper, sugar and salt and saute until the pork is cooked.

Add in garlic and stir fry for another 2 minutes.

Next, add in the jicama, and dried shrimp (if using), and continue to cook until the jicama is slightly softened.

Add in carrots and leek, and cook for a few minutes.

Add in oyster sauce, taste and adjust the seasoning.

If the jicama contains a lot of water, add in 1-2 tablespoon of all-purpose flour to the mixture and cook for another 2 more minutes.

Transfer the cooked filling into a clean bowl and let cool completely.

Cover and chill in the fridge overnight.

Combine wheat starch, rice flour, tapioca starch in a large heat-proof bowl. Give it a mix.

Pour in 600ml of hot boiling water into the flour mixture.

Mix with a wooden spoon, until the dough has cooled a little.

Knead the dough with your hands for 2-3 minutes.

Add in oil and continue to knead until the dough is smooth.

Cover the dough and let it rest at room temperature for about 10 minutes.

Form the dough into a long log and divide into 14g dough balls (for 3.25" diameter dumpling mold).

Flatten the dough by placing it in between a folded piece of parchment paper and pressing it between a tortilla press. (Thickness of dough should be ~1 mm).

Lightly grease the dumpling mold with sesame oil (only the first time) and place the dough in the mold.

Add 1 tablespoon of filling and close the mold firmly to form the dumpling.

Place the dumplings on a lightly greased steaming rack.

Repeat with the remainder.