Pour the milk into a deep heavy bottomed pot. Bring it to boil and when the milk comes to a roaring boil, add the lemon juice (or vinegar) a little at a time (about a tablespoon), and lower the heat. Keep stirring the milk as you add the lemon juice.
After sometime the milk will start separating and a greenish but clear whey along with the curdled milk will start forming. Now immediately stop adding the lemon juice/or vinegar and stop stirring. If too much of the curdling agent, the chenna will be tough and also sour.
Turn off the heat, remove the pot from the stove and allow the curdled milk to sit for about 8-12 minutes. Do not stir. At this stage some people add ice cubes also to prevent milk from further curdling and it prevents chenna from becoming sour and tough.
Place a clean kitchen cloth or a muslin cloth over a colander or strainer. Pour curdled milk over the strainer. Give the chenna/cheese a quick wash with a spray of cold water. This removes the smell of the curdling agent and also prevents the cheese from getting stiff. Allow the whey to drain completely, about 30 minutes.
Tie all the ends of the cloth, squeeze out the excess liquid from chenna and hang it on tab of kitchen sink. Leave it this way for about 2 – 3 hours. When you squeeze there should be no more moisture dripping out and yet the chenna should should be really soft and moist.
Now start kneading the chenna with your fingers at initial stage it will be sticky but gradually it will form into a smooth dough, it takes around 20 – 30 minutes to get the perfect consistency dough.
Divide the dough into 10 rough portions. Roll them in into small sized balls gently in your palms.
Take the sugar,cardamom powder and water in a pressure cooker and boil it until the sugar has completely dissolved and the solution is in roaring boil. Just before you add the chenna balls, reduce the heat to medium-high. If there are too many chenna balls you might have to cook them in batches because chenna balls increase in size once cooked. The level of the liquid should be just high enough that the balls completely submerge. Add chenna balls one by one in pressure cooker.
Cover the pressure cooker and cook it till you get one whistle in low flame. After a whistle,simmer more and keep for another 5 minutes.
Put off the flame and let the pressure gets released by itself,then open the lid to see the rasgullas – by now it would have doubled in size.
Let the rasgullas cooled down in the same sugar syrup. Once rasgullas cooled down completely garnish with saffron and nuts and keep in the refrigerator.
Serve Rasgulla chilled!!