Sally, I have also been searching for alkaline water and golden syrup here in the states but have yet to find either. However, I have found that one can make mooncake with tap or plain water; however, you must let the cakes sit for a day or two to "ripen". I am also testing out seltzer water on my next batch to see if that works as well.
Golden Syrup is also known as light treacle in Britain and is supposed to be relatively easy to find in Europe. I am told a decent substitute is one part honey to one part corn syrup. I have not tried this. The inetrnet may have substitute ideas, you can search for those.
I have had great luck with using a good moon cake crust recipe and then using my own fillings. My children particularly loved the walnuts and date fillings, and I use a mohn, poppyseed filling in the smaller cakes. I have also had good luck with a pistachio filling, but I did not write down the recipe and must try to remake it this year!
Good luck with your moon cakes!
A Note From Betsy at Recipelink:
Lyle's Golden Syrup - ordering info
