let's cook black rice
all you got to find out, is the exact volume of extra water needed for evaporation
You may have a rice-to-water ratio that has been working out well for you, but here what we feel gives that ideal 'chewiness', not too hard, not moist either. First with a pot, then a rice cooker.
Key is to take into consideration that not only water is absorbed into the grains, but that along the process a bit of water evaporates.
Let's break both parts up here.
rice absorbs water in a 1:1 ratio
1 cup of rice
1 cup of water
If you double your batch of rice, double the volume of water.
If you triple the rice, then triple the volume of water.
This amount of water solely depends on your cooking equipment and will always be the same volume, regardless how many batches you decide to cook.
some water 'escapes' while cooking rice,
this loss has to be compensated
find out the amount of evaporation water
gradually add water and taste
Cook first 1 cup of rice with 1 cup of water.
Taste and most likely you will find the texture a bit hard. Add ¼ cup of water. Simmer until all water is gone (keep lid covered). Taste again and repeat until you got the texture that works for you.
Probably you end up somewhere between ¼ (harder (texture) to ¾ (softer, more moist) of a cup.
volume of water for evaporation is fixed regardless the amount of cups of cooked rice
X cups of rice
X cups of water
fixed volume of water for evaporation
For example at home, when we want to cook 3 batches of rice - out of experience we know that with our equipment ¼ cup of water is vaporized - we got to go with 3 + ¼ cup of water.
then, two more things
don't keep rice at room temperature
Either hold the rice warm or refrigerate. Also, reheat overnight leftovers.
cooking rice with a pot
Bring rice to a boil for 5 minutes.
Cover and simmer (medium-low heat) for 25 minutes.
(use the same cup to measure the amount of water)
Fluff the rice and simmer for another 5 minutes.
(get a heavy-bottom pot - we can't stress enough - to avoid the rice to burn or stick)
Turn off the heat and let the rice be for 15 minutes so the grains can firm up.
(keep the pot covered all the time, also at the end when the rice sits)
cooking instructions for a rice cooker and pressure cooker
Often we are asked, what's better: pot or rice cooker?
We feel rice is tastier when using a pot, but a simple rice cooker works just fine, and that's what we - and most people in Thailand - use most of the time.
It's so easy, just follow your rice cooker's rice-to-water ratio recommendation and once ready, the device will shut itself off while the rice is kept warm!
Nevertheless, you can determine the amount of evaporation water the same way as described above.
We are not familiar with pressure cookers, but the same goes here. Define the water volume for evaporation as you would do with a pan and count the time until you open the lid.