I made Tea Eggs years ago (further back than i care to remember,) ;D This is how I done them.
Hard boil your eggs About 7-8 mins, when cool enough to handel crack the shell all over, with the back of a spoon (don't remove any shell) then put them into a bowl and cover with soy sauce, (or tea) and let stand for a couple of day's, (The longer the better) and when you take off the shell "BINGO" Tea Eggs, (I expect their are many other ways to do them, this was mine)
HS