Assembly Method:
1. Simmer the blackberries and umeboshi until liquid begins to reduce and turns syrupy.
2. Combine the pork, onion, umeboshi, cooked blackberries, salt and white pepper in a bowl. Mix until completely homogenous.
3. Set up a station with the gyoza wrappers, filling and a bowl of cool water for folding the dumplings.
4. Place 1 tablespoon of filling in the center of the gyoza wrapper, then put water around the outer edge of the wrapper. Fold the dumpling into a semi-circle, then seal by crimping the front edge and pushing it into the back.
5. Heat oil over high heat in a sauté pan. When the oil is preheated, sear bottoms of the gyoza.
6. Once the gyoza is browned and crispy add ¼ cup of water to the pan, cover and steam to cook through, about 4 minutes.
Optional Steamed Method - Replace steps 5 & 6 above with:
1. Over a boiling pot of water in either a paper lined bamboo steaming basket or perforated steam pot, arrange your dumplings to have 1/4 inch gaps around them.
2. Steam for roughly 5-7 minutes until the wrapper has turned translucent and set firm.