Nigari are salt crystals, mostly magnesium chloride crystals used to make tofu. It is the Japanese name for the bitter salt extracted from sea salt. I'm going to be making tofu in the coming days, and this is the easiest tofu salt to get hold of. It is sold as Japanese Nigari, but if you can't buy it you can also make it.
You will need real sea salt, processed sea salt already has this bitter salt removed and will not work. Look on the label for the presence of magnesium chloride.
Instructions for Making Nigari from Sea Salt
1. Wrap your sea salt in a cheese cloth or place them in a plastic colander.
2. The Nigari salt dissolves faster than other salts, so the aim is to get the salt in a moist atmosphere so that it can drip into a tray, leaving the other salts behind.
3. I used a steamer, with a small plate to catch the drips and a wire stand to stand the bag of salt on. You can see this in the photo.
4. I place the steamer on a very low heat, I don't want the water to boil, just to make the air moist. Once the water is hot I turn off the heat and leave it covered for a at least a day, often longer.
5. The magnesium salts absorb the water far faster than other salts, and drips down into the plate. So the bitter salt that drips onto the plate is Nigari and what is left can be used as cooking salt.
6. You can the drive off the water to make crystals simply by leaving the plate out in the sun. But you can also use the liquid directly to make tofu.