Finely chop the green cabbage and place it in a small bowl with a pinch of sea salt to draw out moisture; let sit for 5 minutes then squeeze dry using a clean kitchen towel.
In a medium mixing bowl, combine the ground pork, squeezed cabbage, tamari, toasted sesame oil, minced ginger, minced garlic, sliced green onions, sea salt, and black pepper.
Mix the pork filling thoroughly with your hands or a spatula until all ingredients are evenly incorporated and the mixture is slightly tacky.
Lay the dumpling wrappers on a clean surface and place approximately one tablespoon of the pork filling in the center of each wrapper.
Lightly moisten the outer edges of each wrapper with water using your finger, then fold the wrapper in half over the filling and pinch the edges firmly to create a tight seal.
Line a steamer basket with parchment paper and arrange the dumplings in a single layer, ensuring they do not touch each other.
Place the steamer over a pot of boiling water, cover tightly, and steam for 8 to 10 minutes until the pork is thoroughly cooked and the wrappers appear translucent.