Seasoning     
Salt    1/2 tbsp
Light Soy Sauce    1 tbsp
Oil    2 tbsp

    
Steps
1)   Remove dirt of salty duck eggs, steam with shell until cook, remove shell
2)   Chop the cooked salty egg into small dices, both white and yolk
3)   Remove dirt of preserved duck egg and shell, chop into small dices
4)   Clean tomato, remove all seeds, chop into small dices 
5)   Heat wok with 2 tbsp of oil, stir fry tomato dices for 2 minutes
6)   Dish up tomato with sauce, add 2 tbsp of cornflour and stir well
7)   Remove shell and whisk egg, add seasoning, all dices and tomato, whisk
8)   Heat wok with 3 tbsp of oil, pour in whisked and mixed egg
9)   Stir fry until cooked, dish up and serve

Remark 
tbsp -     table spoon
Preserved duck egg -
          black colour ( pi dan ) , purchased from dry-food shop in China-town 
Salty duck egg -
          white colour ( xian dan ) , purchased from dry-food shop in China-town