Heat sesame oil in large pan on medium-low head. Sauté garlic until golden. Add mushrooms and salt. Cook for about 15 minutes , stirring occasionally, until most liquid as evaporated. Add green onions and cook until tender.
Prepare dumpling filling station with clean surface, dumpling wrappers, small bowl of water, and pan lined with parchment paper.
Lay out a single wrapper and fill with ½ tablespoon of filling. Dip fingers in water, wet edge of wrapper, fold over, and press edge together to seal. Place dumpling on pan and repeat until filling is gone.
To steam, add the dumplings to a steamer or steamer basket, and steam until the wrappers become translucent (8-10 minutes).
Serve dumplings on a platter with tamari (soy sauce) or mixture of tamari, rice vinegar, and siracha.