Heat the milk: Pour the milk into the saucepan and set over medium heat. Bring the milk to a bare simmer — just below the boil at around 200°F. Stir the milk occasionally, scraping the bottom of the pot to make sure the milk doesn't scald. When ready, the milk will look foamy and steamy.
Add the lemon juice: Remove the milk from heat and stir in the lemon juice. The milk should begin to curdle immediately, but it's ok if it doesn't.
Let the milk stand for 10 minutes: Cover the milk and let stand for 10 minutes to give the acid time to completely separate the curds and whey. At the end of 10 minutes, the curds should be completely separated and the liquid should look yellow and watery. If the milk hasn't separated, try adding another tablespoon of acid. If it still won't separate, check your milk and be sure you are using non-UHT milk; this kind of milk won't separate.
Strain the curds: Set a strainer or colander over a mixing bowl and line it with cheesecloth, a nut bag, or other straining cloth. Carefully scoop or pour the curds into the strainer, letting the whey collect in the bowl beneath.
Squeeze the curds: Gather the cheesecloth in your hand and gently squeeze to remove the excess whey.
Salt the curds: Open the cheesecloth and sprinkle 1/4 teaspoon of salt over the curds. Stir gently and taste. Add more salt if desired.
Press the curds: Transfer the curds (still in the cheesecloth) to a large dinner plate. Shape them into a rough square and then fold the cheesecloth tightly around the curds to form a neat rectangular package. Set a second plate on top of the package and weigh it down. Press for at least 15 minutes or up to 1 hour.
Use or refrigerate the paneer: Once pressed, your paneer is finished and ready to use. You can use it immediately or refrigerate for up to two days. Refrigerated paneer will be firmer and less likely to crumble than fresh paneer.