So below is the way I do it but there are endless other variations. I learnt how to make it from 2 of my sisters and have pretty much stuck with their recipe ever since. I generally make around 1 litre each batch and that way I've got enough for a couple of days.
Ingredients for my brew,you don't have to be exact with this.
40 cardamon pods
1/2 stick of cinnamon
2 tablespoons fresh ginger
Big tablespoon honey.
I put around 700 ml of cold water in a decent size saucepan and whilst it's coming to the boil I roughly crush the cardamon pods and the cinnamon in a mortar and pestle but you can also just roughly chop them up with a knife,I also cut up the ginger finely but don't make too much work out of it. Add the cut/ground up ingredients to the water and simmer for around 5 minutes.
The add the milk and the black tea ( 4 tea bags works well) but I like loose leaf tea and put in around 3 decent teaspoons. Heat the mixture back up but don't boil it. When hot add the honey more or less depending on your taste. You can also use sugar if preferred. Then strain the liquid into a jug and pour yourself a cup and enjoy. You can fiddle around with the quantities of the various ingredients depending on your taste
So now, next time your at a folk festival and walk past the Chai tent, you can take comfort in the fact that you know how to make the real stuff or maybe go in and see how they it.