Rinse the glutinous rice under cold water until the water runs clear, then soak in a bowl of water for at least 2 hours.
Drain the rice thoroughly and spread it out on a large plate or shallow dish.
In a medium mixing bowl, combine the ground pork, tamari, toasted sesame oil, minced ginger, minced garlic, sliced green onion, sea salt, and black pepper.
Mix the pork mixture by hand until well combined and slightly tacky.
Scoop about 2 tablespoons of the pork mixture and roll into a smooth ball, roughly 1.5 inches in diameter.
Roll each pork ball in the soaked rice, pressing gently so the rice grains adhere to the surface and cover it completely.
Place the rice balls into a steamer basket lined with parchment paper, leaving space between each ball.
Steam over boiling water for 18 to 20 minutes until the pork is cooked through and the rice is translucent and tender.
Remove from the steamer and let rest for 2 minutes before serving warm.