Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
  3       Tablespoons   rice wine vinegar 
  4       Tablespoons   vegetable oil 
  1       Teapoon       soy sauce 
    1/2   Teapoon       sugar 
  1       Tablespoon    grated onion 

Preparation:

1. Mix all the ingredients other than oil in a bowl.

2. Add oil gradually into a bowl and mix well.