Warm milk in a pan until 80c and then turn the heat off.
Add vinegar (or lemon juice), put the lid on and leave off the heat for 30 minutes.
Drain the liquid off and place the curds into a muslin bag or cheese cloth (press further with a back of a spoon and twist in the bag to remove excess fluid) and let it drain
Place it in the cloth in a tofu box and leave it in the fridge for 4 hours+
The longer it is in the fridge the firmer it is.
Flavours (liquid smoke etc) can be added at the heating stage.