Line a large fine-mesh sieve with several layers of cheese cheesecloth or use man’s handkerchief or thin cotton cloth. Set over a large bowl.
Take milk in a heavy bottom pan or patila. Bring it to a boil on medium heat. As soon as it starts boiling turn off the heat and remove it from the heat (if using electric/coil stovetop).
Then start adding lemon juice and keep stirring.
As you stir, you will notice that milk has starts to curdle. If it does not curdle, then you can add more lemon juice. But do not add too much at the beginning.
You will see the greenish whey and milk solids(chenna) are separated. Drain and separate them using a prepared strainer.
Then wash the chenna under running cold water, so all the sourness from lemon juice/vinegar will wash away. Also, as it cools down, it stops further cooking and prevents it from becoming chewy.
Now gather the edges of the cloth, tie and twist, press lightly to remove all the moisture.
Your chhena is ready to use in the sweets.
Notes
I got 150 grams of chenna from 1 liter of milk. Sometimes I get more, sometimes I get less. The quantity output depends on the quality and fat content of the milk you have used.
Always use full-fat milk (whole milk) - preferably cow’s milk.
Please use freshly squeezed lemon juice (not from the bottle).