In a large bowl, combine ground meat, garlic, ginger, soy sauce, sake, green scallions, sugar, salt, black pepper, egg, cornstarch, and sesame oil.
Mix in one direction for 1–2 minutes until the mixture becomes sticky and well combined.
Fold in chopped cabbage and mix until fully incorporated. Cover and refrigerate for 20 minutes to marinate.
Scoop about 1 heaping tablespoon of filling onto parchment paper, spacing evenly.
Brush some water onto one side of the wrapper then place it over each mound of meat.
Press and gently squeeze in circular motion and shape the wrapper around the filling to secure.
Heat a pan over low medium heat and add avocado oil.
Place dumplings wrapper-side up, leaving space between each.
Cook uncovered for 4 minutes or until bottoms are lightly golden.
Pour in ⅔ cup water, cover and slightly increase heat to simmering.
Steam for 5–6 minutes until most of the water has evaporated, then remove the lid.
Adjust heat to medium and add 1 tablespoon oil to the pan so the dumplings crisp up.
Cook uncovered another 5-6 minutes or until golden and crispy.
Flip and cook the top side 3-4 minutes or until golden brown.
Serve hot with dipping sauce made from soy sauce, rice vinegar, ginger, sugar, and sesame oil.
