Separate the white and green parts of the napa cabbage leaves. Finely dice the white stems and chop the green leaves.

In a mortar and pestle or food processor, pound the white peppercorns until fine, then add the minced garlic and chopped ginger, pounding into a smooth paste.

In a wok or large skillet over medium heat, add a tablespoon of oil and the garlic-ginger paste. Sauté for about 2 minutes until aromatic.

Add the diced napa cabbage stems, increase the heat to medium-high, and sprinkle 1/4 tsp of salt. Cook for about 4-5 minutes until soft and translucent. Add the cabbage leaves and cook for another 2-3 minutes until wilted. Remove from heat and let cool.

In a large mixing bowl, combine the ground pork, remaining 1/4 tsp of salt, soy sauce, optional dashi powder, sesame oil, tapioca starch, and sugar. Knead with hands for at least 5 minutes until smooth.

Gently fold in the cooled cabbage mixture and garlic chives into the pork filling until well combined.

Scoop about a tablespoon of filling into the center of each dumpling wrapper, moisten edges with water, fold to seal, and pinch at the top to create little pleats. Freeze immediately if not cooking right away.

In a small bowl, mix rice vinegar, soy sauce, and optional sugar and chili oil for the dipping sauce.

Heat a non-stick skillet over medium heat and coat the bottom with oil. Arrange dumplings in the skillet, frying for 3-5 minutes until golden brown.

Lower heat, add 1/4 cup of water to the skillet, cover immediately and steam for about 3-5 minutes until fully cooked.

Serve crispy side up with a drizzle of your homemade dipping sauce.