Mix lemon juice in 1/2 cup of water and keep it aside. Boil the milk in a heavy bottomed pan over medium heat while stirring occasionally. Make sure not to burn the milk.
When the milk comes to boil, add the lemon juice gradually and stir the milk gently. Once it splits, turn the heat off.
When the milk fat has separated from the whey, drain the whey using a strainer line with a muslin cloth. Wrap the curd in a muslin cloth and rinse under cold water. Squeeze it well.
To check if enough water is drained out of the paneer, take a little piece of paneer on your palms and rub it with your fingers. After rubbing the paneer for about 15-20 seconds, you should be able to make a firm but smooth ball.
Once the paneer is drained, place on a dry and clean surface to knead the paneer for 3-4 minutes until the paneer almost rolls into a smooth and soft dough. Knead the paneer by dragging the palm of your hands hard on the paneer.
Keep scooping it back together and knead more. If the paneer is too crumbly, add a teaspoon of water. Your palm will be little greasy. Divide the dough into 12 equal parts and roll them into smooth balls.
To make the balls, apply some pressure at first and then release when forming the balls. Mix sugar and water together in a pressure cooker on a high heat and bring it to boil. Add the paneer balls and pressure cook it on a medium heat. Then turn off the gas.
Wait for 10 minutes, then pour cold water on the cooker before opening the lid. The rasgulla will be a little spongy.
Refrigerate it for a while before serving.