Cooking whole dried soybeans
Until fairly recently I had a blind spot when it came to the humble soybean. I regularly consume soy products like soy milk, tofu and okara, not to mention fermented soybean products like natto and tempeh. And green soybeans or edamame are always a great snack.
But for some reason, I didn't really get into eating the whole dried (and cooked) soybean. It's not that they are that much harder to cook than other dried beans either.
In any case, I've rectified that situation and now I cook up a batch of soybeans quite regularly and store them in the freezer. Plain boiled soybeans are amazingly delicious, and just packed with nutrition. The cooking liquid is so rich that it can be used as a very nutritious stock or dashi for making soups and such.
There are a couple of points to watch out for when cooking whole soybeans, which are noted below in copious detail.
Step 1: Wash and pick over
Rinse the dried soybeans, rubbing them together gently to remove any surface powdery residue , and pick out any dark or discolored beans. These will not cook properly. If any of the hulls work themselves loose while you're washing, pick those out too.
Step 2: Soak overnight
Soak the beans in water to cover for several hours or overnight. You may need to soak them a bit longer than other types of beans. Also, the bring to a boil then let sit for an hour method of speeding up bean cooking does't really work well for some reason.
After soaking, you can optionally split the beans by squeezing them gently. (An alternative is to use a food mill to split the dried beans, but I don't have such a device so if I want the beans split I do it after they are saturated with water.)
Step 3: Use a big pot
Just like soy milk foams up like crazy while it's being cooked, soybean cooking liquid will bubble up quite enthusiastically, all over your stovetop if you don't watch out. So the dried soybeans should not come up to more than 1/4th of the height of your cooking pot, and the cooking water should only come up to about 1/3rd of the height maximum. In other words, use a big pot, or cook less. This is particularly true if you're using a pressure cooker - the viscous cooking liquid may even clog up the works, so be careful. (My pressure cooker can handle about 3 cups of dried beans.)
Step 4: Bring to a boil, then skim off the grey stuff
Whether you are using a pressure cooker or a regular pot, you should first bring the soybeans to a boil, then skim off the greyish stuff that will rise to the surface of the water.
Step 5a: Using a pressure cooker
After you've skimmed off the initial grey stuff, put a heat-safe plate that is a smaller than the circumference of the pot on top of the beans. This plate helps to keep the beans from dancing around, and also prevents any loose hulls from rising up and possibly clogging the pressure valves. Once it's reached pressure, lower the heat and cook for 20-25 minutes. Turn off and let cool naturally until de-pressurized.
Step 5b: Using a regular pot
Heat up to a boil, then put a heat-safe plate or an otoshibuta on top of the beans. Cooking time is about 3 hours, but don't worry, you don't have to watch it continuously for that time. Top up with additional water from time to time if it seems to be cooking off, and skim off any grey stuff. A slow cooker would work too. The beans are done if you press one between your finger and thumb and it's soft, not crunchy. (Or just eat one!)
Step 6: Draining and removing the hulls
Once the beans are cooked using either method, stir then let them sit a bit - the loose hulls will rise to the surface. Skim these off. Strain the beans, reserving the liquid to use as a vegan stock. (Don't get too concerned about a few loose hulls left in. Removing those hulls is just a good idea because they tend to end up undigested and loose in your innards, which may cause you to rooty-toot-toot a bit more than you may want to and such.)
Step 7: Optional oven drying
The beans at this stage are pale and rather soft. You can use them as-is, but one thing I like to do to at least half the beans is to slow-dry them in the oven. This makes the beans firmer and meatier, and more suited to use as a meat substitute.
Just spread out the well drained and cooked beans on a baking sheet, and put into your oven at the lowest possible heated setting. On my oven that's 50°C or 122°F. Leave the sheet of beans in there for about 2 hours, turning occasionally. They will shrink to about 20% and turn a light reddish brown. If you taste one it should be just a bit chewy but not hard.
You can use these dried soybeans coarsely ground in a food processor as a ground meat substitute in pasta sauces and such, or to make soy burgers and so on. (You can dry canned soybeans in this way too.)
Storing and freezing
I store un-dried soybeans in freezer bags with a little bit of the cooking liquid. These are used in stewed dishes, soups and such. The dried beans are stored on their own in freezer bags. The cooking liquid can be frozen too.
So there you have it. It may seem complicated, but it really isn't once you've done it once. And the results are worth it especially if you are a vegan/vegetarian. And it's wonderfully cheap too.
Now, of course you can turn these boiled soybeans into fun things like tempeh and natto. That's for another day....