Ingredients
2 litres of chicken stock 
150ml dark soy sauce 
150ml light soy sauce 
100ml shaoxing rice wine 
2 star anise 
2 cinnamon sticks 
½ tsp Szechuan peppercorns 
1 heaped tbsp rock sugar 
2 pieces tangerine peel or 2 tbsp tangerine chips 
2 cloves 
½ tsp white peppercorns 
80g ginger 
4 spring onions 
4 garlic cloves 
1 black cardamom pod 
1 tsp sesame oil

Method
Put all the ingredients into a very large saucepan, bring to the boil and then simmer for 25 minutes.  You can then use it immediately or put it into the fridge or freezer for later use. 

The idea of a master stock is to use it to poach with, you re-use it again and again (think sour dough starter).  The rich flavours will develop over time and it will improve with age.  You can either keep in the fridge for a week or freeze.  Always boil before using when you first reuse it.