you're using the wrong kind of rice. That particular kind of steamer is meant to be used for cooking glutinous rice, not short (sushi rice) or long (jasmine rice, etc.) grain varieties of japonica rice. Glutinous rice is the only kind of rice that will give you the kind of results you're looking for with this cooking method, other kinds of rice just aren't suited for this treatment and will do better simmering in a pot on the stove or an electric rice cooker.
Don't get me started on how infuriating it is that restaurants call rice cooked in a rice cooker "steamed" rice when it's really just plain old simmered rice! That's a lot of where the confusion in this thread is coming from, and it's all due to a misuse of cooking terms by restaurateurs who should know better.
Okay. So I'm using a cooking method that's incorrect for the variety of rice I'm using. If I want to make Onigiri or Sushi, I have to simmer? I guess that makes that the traditional method. ... and requires an extra pot on my stove, but I'll get some clay pots
for this maybe.
Mind you I've also got sticky thai rice (that I want to steam... it's the correct variety for this), and bamboo steamers that sit on a Wok (which should do the same job as this). So, same deal: can't cook sushi rice in that either, might be able to do sticky thai rice.
-- Don't try to seal the rice in a container for rinsing, that's just adding more hassle where you don't need it. Just put the rice in a bowl that can hold twice the amount of rice you're using, fill with cold water, mix well with your hand, then pour most of the water out while using your hand to retain the rice. Repeat twice (for a total of three rinses) and your rice will be as well-rinsed as it needs to be.
Or put it in a what is that thing called, collander? And run clear?
-- Soak for a long time. Six to eight hours at minimum. Overnight wouldn't be a bad idea. You're after a fluffy, sticky texture in the final rice, which means you need to load it up with as much water as you can before applying the steam. The steam just heats the water already present in the rice to cook it (gelatinize the starch, that is), it does not add much water to the rice on its own. Steam is much to energetic for that, it transfers some heat and then it leaves.
Okay, that clarifies that. The rice is as wet as it gets. Should I soak in the fridge, or on the counter? Something tells me that 4000 years ago, Taiwanese people didn't own refrigerators; then again, I can build a refrigerator that runs directly on kerosene heat (yes, no mechanical parts, no electricity, apply fire get coldness), so I may be wrong. Still, warm/hot water penetrates better due to lower viscosity right?
-- Use a chopstick or your finger to poke some holes through a deep rice bed (like this) to allow steam to move through more freely. Believe me, the end result is more even cooking.
-- Steam for as long as you think you can get away with (at least for sake rice). You can start checking for doneness after 30 minutes, but I don't usually even bother until my 45 minute timer goes off. Even then, I often have to add another 15 minutes for the rice to reach the level of gelatinization I'm after. For steamed glutinous rice, most Thai cooks I know say 45 minutes is how long they steam.
So longer != damage? I thought "too long" would be a horrible error.