Add the seeds to a blender jar along with salt. Squeeze the lemon juice(optional) into the blender.
Pulse a few times, briefly for 10 to 15 seconds, you want to make sure the seeds are still mostly intact but the juice around the seeds is released. Crushing the seeds will make the juice gritty. [But the seeds have medicinal values so weal ways crush them and pass through a very fine strainer. so it is up to you]
Place a fine mesh strainer over a large bowl and transfer the juice. It is important to use a fine strainer or a thin cheese cloth if you do not want the juice to be gritty
Press the pulp against the strainer with the back of a spoon to squeeze out every bit of fresh juice.
Drink your pomegranate juice immediately as is, store in the refrigerator for later culinary uses, or dilute with seltzer water to stretch the juice further. If it is too strong for your taste, you may mix it with other fruit juices or plain water.