How to make a soy sauce?!
Answers: I searched the web and couldn't find one for you, just a substitute made with beef boullion. I imagine it would be time consuming, as it is made by fermenting soy beans (and in the US, often contains wheat too). It's pretty inexpensive, and even cheaper if you live near a health food store who sells it in bulk (you pour into your own container) - so why not buy it instead?
Sweetened Soy Sauce:
1 cup soy sauce (Japanese, not Chinese)
2/3 cup sugar (I use about half that)
1/2 cup sake or sherry wine
1 onion, roughly chopped (10 cm long) or 1/2 round onion, roughly chopped
1 ginger, thinly sliced (1 knob)
15 g cinnamon sticks (2)
star anise (1-2 stars)
15 g dried orange peel
Put all ingredients in pan, bring to boil, and simmer over low heat for approximately one hour, until liquid has reduced to about 2/3.
Strain, cool, and store in fridge for up to one month.
Use in same quantities as Oyster Sauce.