Toss the celery, carrots, and onions into a big 8-quart saucepan with the melted butter. Keep stirring occasionally until the onion becomes smooth and transparent. Cook for another 30 seconds after adding the garlic.
Toss in the shredded chicken and the chicken broth. Add pepper, salt, bay leaves, and parsley for seasoning. While you're preparing the dumplings, bring to a boil, then reduce heat and simmer.
For Glutinous Rice:
Toss the salt, baking soda, and flour together in a large basin. Coat the flour mixture with the grated cold butter, which you may do using a cheese grater.
Combine the flour, milk, and water; mix until dough forms a ball. If necessary, you may knead it many times in the basin.
Cut the dough into inch pieces and put them into the soup. Simmer, covered, for fifteen to twenty minutes, or until dumplings float to the surface of soup.
Add the cornstarch and cold water mixture to the soup to thicken it. It will thicken as you stir it continuously.
