Put the milk in a large pot and heat over medium heat, stirring occasionally, until it just comes to a boil. Do not heat it too quickly or let it scald.

Take the pot off the heat and stir in the lemon juice. Cover the pot and let sit for 10 minutes. At this point, the curds and whey should have separated, and there will be a yellowish, watery layer (the whey) on top with the curds at the bottom.

Line a strainer or colander with the cheesecloth and set it over a large bowl. Pour the separated milk through the strainer. You can pour out the whey or transfer it to another container to save for another purpose (some people use it in baking, smoothies, or in their next batch of paneer.) Let the curds sit in the cheesecloth in the strainer until they are cool enough to handle, about 5 minutes. Gather the cheesecloth around the cheese and squeeze it gently to remove the remaining liquid. Stir in the salt.

Pat the cheese into a flat patty, about 1½ to 2 inches thick.

Wrap the patty in the cheesecloth and set it on a plate. A pot or another plate on top and weight it down with a large can of tomatoes or something similar. Let stand for 30 to 60 minutes. Drain off any liquid that has collected on the plate, and then unwrap the cheesecloth. Use or eat the paneer immediately, or wrap it in plastic wrap and store in the refrigerator for up to 3 days. Paneer can even be frozen (again, wrap it in plastic wrap and then pop it in the freezer, where it will keep for at least 3 months).