Over medium heat bring milk to boil. Keeping the lid on will speed up the process but don't forget to stir the milk every now and again.
Pour the lemon juice or vinegar into the hot milk and stir. The milk should curd immediately. If not, just add a bit more lemon juice / vinegar.
Strain the curd from the whey, use a cheesecloth or a simple kitchen cloth and a colander or sieve. Rinse the curd with cold water to remove traces of lemon juice or vinegar and quicken the firming of the curd.
Twist the cheesecloth and squeeze out as much liquid as possible.
Shape the curd into a disc or any desired shape.
With the cheesecloth still on, weight it down for a couple of hours. If there is enough space in the fridge, set the whole thing there until cooled off completely. Once the paneer is chilled, it's ready to be used.
Enjoy!