Boil 1 liter full-fat milk in a heavy pan
Add 2 to 3 tablespoons lemon juice or vinegar slowly, stirring gently, until the milk curdles
Turn off the heat
Strain the curdled milk through a muslin cloth or fine sieve
Rinse the chenna under cold water to remove the sourness
Squeeze out excess water
Hang or press the chenna for 30 to 45 minutes to remove more moisture
Knead the chenna with your palm until smooth and soft
Shape the chenna into small, crack-free balls
Prepare sugar syrup by boiling 4 cups water with 1 to 1.5 cups sugar
Add a few cardamom pods if desired
Drop the chenna balls into the boiling syrup
Cover and cook on medium heat for 15 to 20 minutes
Keep the syrup boiling gently while the balls expand
Turn off the heat and let the rasgullas cool in the syrup
Chill before serving