Place the buckwheat in a pot. Add the onions, celery, and water, and sea salt. Cover, and bring to a boil. Reduce the flame to medium-low and simmer for about 15 to 20 minutes. 

Season with a small amount of soy sauce for a mild salty taste, and add the minced parsley. Reduce the flame to low and simmer for another 4 to 5 minutes. 

Serve hot.