What is a vegetarian alternative to putting pork in bak chang?!

Cubed tofu is ok but you will need to marinate it for a few hours in a sauce or herbs and spices.Always buy silken tofu because it is firmer and less watery. You could also try quorn chunks, mince and fillets that are low in fat and can be used to replace meat in any recepe.

I've no idea what bak chang is but putting in tofu as direct meat substitute is not always successful. The basic problem is that tofu is pretty much flavourless, so it is OK in things which have plenty of other flavours like stews and curries but not so good in situations which rely on the meat for taste. As as a long term veggie I find tofu quite good in any situation but for the newbie I would recommend having plenty of accompanying flavours and not to use to much tofu. If bak chang would be nice without the pork anyway, then go for the tofu.

There are also plenty of meals using Quorn. Quorn is pretty flavourless too in its raw form but recently there seem to plenty of products in which it has been treated to be more like a fake meat.

I would put quorn in it.