
In a small saucepan, combine mirin and sake over medium heat.
Bring it to boil allowing the alcohol contents in mirin and sake to evaporate.
Add the sugar and soy sauce to the mixture and stir well until it dissolves completely.
Reduce heat to low and let it simmer for about 20 minutes or until it has reduced by half.
Add a pinch of salt.
Remove from heat and let cool completely before using or storing.
Store it in a clean sterilised jar or air-tight container.