Heat milk in a pot. Bring it to a boil. Then turn the flame off. Allow it to cool down. (approx 5 minutes)
In a bowl, pour lemon juice and water. Give it a mix.
Pour this lemon mixture to the milk, 1 tbsp in at a time. Stir continuously but be gentle. As soon as the milk starts curdling, stop adding this mixture.
Take a large bowl and place a strainer over it. Line the strainer with a muslin cloth. Pour the curdled milk or chhena into the strainer. Pour cold water over it and wash it off. This will remove any acidity from the chhena. Squeeze out all the water.
Take the chhena out in a plate and knead it for 5-6 minutes or until smooth.
Add sugar, lemon essence and turmeric powder. You can use yellow food colour if you like.
Knead it again for 3-4 minutes.
Heat non-stick pan on low heat. Add the chhena mixture. Cook for 3-4 minutes, while stirring continuously. Make sure it remains smooth and don’t overcook.
Take it out in a plate and allow it to cool down. Divide the mixture into small balls. Slightly press each ball. Make a design on the sandesh with the help of a toothpick.
Sprinkle lemon zest and serve.