Bring the milk to the boil in a heavy-based saucepan.
Once the milk starts to boil and rise up, stir in the yoghurt or lemon juice. Keeping the milk on the heat, stir gently to help the milk curdle; it should only take about a minute. If it does not separate, add the rest of the yoghurt and keep stirring. The curds will coagulate and separate from the watery whey.
Remove from the heat.
Line a large sieve with muslin or cheesecloth and place over a large bowl or saucepan. Strain the cheese into the sieve and run some cold water through it. Discard the whey or use for another purpose.
Wrap the cheese in the cloth and hang from the kitchen tap over the sink to allow the excess water to drain for 20 minutes. Then, keeping it fairly tight, put the paneer onto a clean work surface. Place a heavy weight on top for 30-40 minutes, or until it is flattened into a firm block. (You can refill the same saucepan with water and place it on top as a weight). Then cut into cubes or crumble, depending on how you want to use it.
Store any unused pieces in the refrigerator in water and cover. You can also freeze the paneer in an airtight container. Defrost thoroughly before use. It is delicious when served with a sprinkling of sea salt, freshly ground pepper and a drizzle of olive oil.