Slowly and gently bring the milk to 185 to 194 degrees F (85 to 90 C). Hold the milk at temperature for about 20 to 30 minutes, then cool to 170 F (77 C).

If using lemon juice, gently warm it to around 170 F and then add it to the warm milk. Stir to incorporate.

If using citric acid, dissolve 1 tsp citric acid in 2 cups warm water (170 F). Add the solution to the milk and stir to incorporate.

Allow the milk to sit undisturbed for about 10 to 15 minutes. After about 10 minutes, check to see that the whey is clear. If it's still cloudy, add another tablespoon of lemon juice or a pinch of citric acid dissolved in water. Stir gently to incorporate and wait a few more minutes before straining.

To strain, pour the curds and whey into a colander that's lined with a double layer of damp cheesecloth. (Reserve the whey for another use or discard.) If you're adding salt, stir it into the curds at this point.

Wrap the cheesecloth around the cheese and hang to drain for about for about 30 minutes.

Once drained, place the curds (still wrapped in cheesecloth) between two cutting boards or plates. Place 8 to 12 pounds of weight on top (about a gallon of water or a few canned goods). Press the cheese for 15 to 20 minutes, or longer if you prefer a firmer cheese.

Remove the weight and unwrap the cheese from the cheesecloth. The cheese is now ready for use, or it can be stored tightly wrapped in the fridge for later.

Paneer is best fresh and I'd suggest using it within 2-3 days. It will keep for 1 to 2 weeks if tightly wrapped in the refrigerator.