Ingredients:
3 tbsp corn flour-blended with 1/2 cup water
2 tbsp vinegar
2 tsp salt
2 tsp soya sauce
1/2 cup tomato puree
2 tbsp chopped celery or 1/4 tsp celery salt
1/4 tsp ajino moto, optional
2 cups water

Method:
Mix all the ingredients, bring to a boil and simmer for 1/2 a minute.