Add water, soy sauce, sugar and spice powder bag to a large pot. Bring to a simmer until sugar is dissolved. Add in eggs. Bring sauce to a low simmer and place lid on pot, leaving it slightly uncovered, allowing enough heat to escape so that your mixture does not boil over. Let eggs stew for about 30 minutes at the low simmer. After 30 minutes, rotate eggs so that the lighter colored side is now on the bottom, and stew another 30 minutes at low simmer. Turn off heat.
Allow eggs to soak overnight in soy sauce mixture, then rotate again in the early morning for a few hours so that the eggs will be an even shade of brown. When ready to eat, gently re-heat the eggs in the pot before serving.