How can I make 'Santon sauce'
From what you have described it sounds like Santon sauce may be a variation of Shandong sauce which is often served in Chinese restaurants alongside Crispy Skin Chicken. Here is a basic recipe that can be found on many internet sites. Perhaps it can be a starting point for you.

2 garlic cloves, finely chopped
2 chilies, finely chopped (I finely strip them rather than chop)
2 scallions, finely chopped (I thinly slice them)
1 tsp sugar
1 tsp sesame oil (I always use the light version)
2 1/2 Tbl chicken stock
Pinch of MSG
3 tsp dry sherry
2 tsp wine vinegar 


Heat a wok and add the garlic, chilies, onions, sugar, and sesame oil. Stir fry for 1 minute. Then add the chicken stock, MSG, sherry and vinegar.
Bring to a boil and then simmer for 20 seconds.


I have found that the flavor varies depending on the type of chilies, sherry, and vinegar used. You can try different types of each to get the particular flavor profile you are looking for. 

If you try this and get the taste you want I would be interested to know the final ingredients.