In a large pot, bring the broth, onion, ginger, carrot, celery, and soy sauce to a boil. Reduce heat, cover partially, and simmer for 20 minutes. Strain the broth; discard the solids. Return the broth to the pot and bring to a boil. Add a few of the dumplings, being careful not to crowd the pot. Simmer until the dumplings float on the surface and the shrimp inside turns pink (cut one in half to check), 3 to 4 minutes. Use a slotted spoon to transfer the dumplings to a plate; set aside. Repeat with the remaining dumplings. Add the peas and simmer until bright green, about 3 minutes. Return the cooked dumplings to the broth to warm. Ladle the soup into individual bowls.