ahhh brings back memories https://www.teas.com.au/TeaCategoriesDetails.aspx?TblID=302&CatID=12
This is a good place to start on a good recipe. I don't know whether it's the best place to buy tea though.
1/3 evaporated milk 2/3 tea (a blend seems best, ceylon, english breakfast, keemun, and assam would be a good teas to mix , maybe throw in a pinch or so also of a fruity flavoured tea such as lychee)
sugar/honey/sweetened condensed milk added after all done, according to your own taste
According to http://cd1.edb.hkedcity.net/cd/itil/lxp/Projects/Team_007/eng/interview_restaurant.html
the leaves are fried before brewing, and then the tea is baked slightly after brewing, then milk is added
I think aerating is a crucial step too, both sites mention this, and I would believe what that hong kong site says because its a real deal dai pai dong owner in the interview.