Put the warm water and dried shiitake mushrooms together in a bowl and let them soak for at least 30 minutes. Then strain the stock through a fine-woven, cloth-lined or fine-mesh strainer to remove any foreign matter. Put the stock into a stock pot for cooking the hot pot. Trim the stems off of the mushrooms, rinse the caps to remove any gritty material, and then squeeze out the excess liquid. Slice the caps into very thin strips and set aside.

Combine the ground chicken, egg, chopped leek, grated ginger, and sea salt together in a bowl and set aside.

Combine the chicken stock with the shiitake mushroom stock in the stock pot and add the sliced shiitake mushrooms. Place the stockpot over medium-high heat. When the stock begins to boil, reduce the heat to maintain the stock at a simmer.

Scoop tablespoonfuls of meat mixture with one spoon, then use a second spoon to shape the spoonfuls into balls and gently drop them into the simmering broth, one at a time.

Let the meatballs cook for one minute and then add the cabbage, carrot, and cremini mushrooms.

Cover the pot with a lid and let the hot pot cook for about 5 minutes, adjusting the heat as necessary to maintain the stock at a gentle simmer. The hot pot is ready when the vegetables are cooked through and the meatballs are no longer pink in the center. Season the hot pot with the freshly ground black pepper and serve.