It can be eaten raw, but normally is used as an ingredient
Tempeh has been made for a long time in the Far east, it is not easily available and it is expensive to buy and cheap to make. It is an unusual food, it is not much like anything else.
If you want to have a go, you need to get some mycelium spores, I get mine over the internet from Erik at http://www.tempeh.info there are some excellent recipes on that website as well, I recommend tempeh with tahini.
If you want to scare your friends after they have eaten it and made lots of nice compliments you can tell them that it's "mouldy beans" which is almost true.
Step 1: Soak the Beans
I use organic soy beans, these are smaller than the beans that are grown in the Americas.
Nearly all the soy beans grown in the Americas are now Genetically Modified to allow them to be weed killer resistant, personally, I like my food as natural as possible with as few residual pesticides and herbicides as possible, eating part of a plant that has been deliberately sprayed with poison seems counter intuitive to me.
You can make as big or small a batch as you like, this is just a 1lb/500g bag.
Step 2: De Husking
There are lots of ways of doing this.
I spread a few beans on a clean tea towel
Spread them out, and wrap them up
Then using a rolling pin, pop the beans, once you have done it a few times it is not so hard. You don't want to crush them to little bits or leave them whole. Of course a few remain whole and a few get crushed, but most want to be split in two.
Step 3: Remove the Skins
It takes several fills of water to get it mainly beans. Use a clean sink, you can scoop them up and have another go if you make a mess of it.
I stir the beans up and pour the water out whilst it swirls the skins up.
Step 4: Part Cook the Beans
The acid from the vinegar helps prevent any unwanted contamination and optimises conditions for the growth of tempeh.
They need a little skimming as the water get a bit scummy.
Once they are cooked, we drain them and put them.
Step 5: Prepare to Inoculate
Drained is not dry enough, so we put them back on the heat and heat them for a few minutes to drive off more water.
Once they are dry enough, leave them to cool. I put a lid half on them, without a lid, they dry out completely, with the lid on they go soggy.
Step 6: Prepare Some Bags While the Beans Cool
Fold the bag up, and then pierce it, you need something thicker than a needle, to do it. I am using a corn cob holder and getting 2 holes for the price of one!
I like to have the bags filled to about one third of their capacity, and fold it so as to make a nice slab about 1.5 inches (40mm) thick.
If you don't use all the bags this time you can use them next time.
Step 7: Inoculate and Bag
We don't want to stick our fingers in or anything that is not really clean as it may have other fungi spore on it and it might ruin our tempeh. I just feel the outside of the pan.
Working with 1lb (500g) of beans, I take a teaspoon of starter and sprinkle it over and stir it in. I normally do 2 half spoons and stir twice. You can use less starter, but you run the risk of not getting a good mix and getting areas that are not well covered. The starter is not expensive, so I don't skimp on it.
It is really important to mix it in well, otherwise you might get bald spots in your tempeh where the mycelium has not grown.
Once really well mix, put it in the bag(s) when you start out, you might want to use a couple of bags and try incubating them in different places. I fold the bag back over the contents to make a slab about 1.5 inches (40mm) thick.
Step 8: Incubate It
I have made myself a rather fancy incubator, using and old fridge, a thermostat and a light bulb. but you don't need to do this, you can do it in the airing cupboard.
Having an incubator and controlling the temperature get me tempeh in 24 hours
The main reasons for it going wrong are keeping it too warm and not mixing enough.
Step 9: Harvesting
You now need to cool it down, it will keep on growing unless you do. Put it in the fridge and let it cool. Once in the fridge it will keep for a week with no problems, you can also freeze it.
There are two main problems you might encounter.
1/ Beans that go slimy and smelly, this tends to happen if the tempeh gets too hot during incubation. It is the result of bacteria, apparently whilst smelly it is non toxic, I still throw it when this happens.
2/ Sporation, the life cycle of the mycelium is to grow and then when it has filled the area available to reproduce, to reproduce it makes spores, these are black. There is NOTHING wrong with this, the tempeh is still fine. Indeed some people prefer their tempeh "very ripe" and it has a different flavour.
I have NEVER experienced any fungal contamination, however should you find any unusual growth, then it would make sense to be better safe than sorry and ditch it.
So you can see what sporated tempeh looks like, I have allowed some to get "ripe" so you can know what to expect. Some people prefer their tempeh very ripe, sporation is not a fault, it is not bad.
Sporation naturally happens towards the end of incubation, everything should be white in the early stages, the green/blue/black dusty spores only develop at the end.
Mixing well helps avoid development of mycelium at different rates and gets you even growth and helps avoid one end sporating whist the other not getting fully colonised.
Step 10: Advanced Tempeh
Soy Bean tempeh is one of the safest foods going, manufacturers in the USA claim there have been no recorded cases of food poisoning.
Using a starter formulated for grains, the most unusual thing I have made is tempeh from wholewheat pasta spirals.
The normal protocol is to mix Soy beans with additives, rice, grains, sunflower seeds and so on.
There are a couple of notable really exotic versions; tempeh bongkrek, is made from coconut presscake or the residue from homemade coconut milk. This tempeh is noted because it is one of the few types of tempeh that can get infected and become poisonous. Is now illegal to make or sell it in Java, yet it's popularity endures as despite it's illegality it is still made.
Corn based tempeh can also get contaminated and be poisonous.
I suggest you get ordinary soy bean tempeh mastered and exercise some caution when experimenting with other substrates.