"Sake!" You can yell for a serving of it and you'll feel like a samuari. You can drink it warm, clear as vodka - with that 'water of life' burn - or drink cool, milky rice wine that tastes like amazake and smooth champagne.
What I've made here - and what I recommend for the homebrewer - is a more sour, rustic, homestyle sake, like the itenerant ronin might have gotten from an indifferent housewife who'd much rather have been left alone with her cats than get all mixed up with wandering mercenaries, no matter the thrill of the romance.
So, here's what you'll need:. All this will be explained later, so if you don't get a point, just keep reading - that's life advice, kids. Also, a word on CLEANLINESS will follow.
1 kg (2.2 pounds, you American dolt) of short grain rice.
200g of koji
A colander that won't let rice through
Some muslin cloth.
An appropriate fermentation vessel
Very clean water
Here's some specifics:
The rice: Get a short grain sticky rice. Many speciality stores stock sushi rice or short grain sticky rice. Visit your local Asian market, your local coop, and stay out of Whole Foods, because they're weird kale-powered aliens who plan on harvesting your inner juices. That's why they want you to be so healthy - so your essence is best for The Harvest.
If you can't find sushi rice or sticky rice, Arborio rice will work nicely. For whatever reason, it tends to be more expensive. I dunno.
The koji - if you're lucky, you'll know someone who has koji. If not, you'll need to order it online, likely. Rare is the local shop that carries koji. You can get it online, no problem.
A WORD ON CLEANLINESS: In brewing, most people try to attain a sterile environment. For the homebrewer, this is next to impossible. From fermentation circles, I have heard the aphorism, "Clean, but not sterile," and that's what I strive for. (Thanks, Lauren) Wash your hands, clean everything with soap and water, rinse well, and use boiling water for any sort of sterilization. Try to avoid bleach and chlorinated water - you're attempting to harbor microbial life and make it work for you, and it can't very well do that if it's dead, can it!?
For clean water, I like to boil tap water then let it sit overnight with a lid on. It's clean and it has minerals. if you want to go to your local coop or fancy water place and get a few gallons of reverse-osmosis filtered water, that's very good too - for most of your homebrew stuff, the mineral mix isn't vital. Plus, it's clean and has zero aftertaste.
ANYWAY, back to making sake. Wash that rice in tap water. In the colander. Wash it once, then again. Now let it soak for 45 minutes and rinse it off twice. You're basically trying to get all the dust and silt off the rice - it can contribute to off flavors.
Now, let it drain dry for like an hour. You'll want it to be fairly dry. It doesn't have to be bone-dry, but it will need to NOT be wet.
Now comes the tricky part. You want to steam the rice without getting condensation and water on it. So line a steamer with muslin cloth and lay a layer of rice on it - the thinner the layer, the better, but you do want to get it all in one go. Don't let the water touch the bottom of the rice, and make sure your muslin cloth is wrapped over the top so the dripping condensation doesn't run through the rice.
Steam your rice for an hour-ish. It may take longer and it may not take that long. Don't let your steamer run out of water. Run the steamer low if you can.
The rice is done when it's just a bit crunchier than you would like it to be before serving it.
Now, paddle all that rice into your Earthen crock. Pour in a quart of room temperature water, put a tight lid on it and let it cool. This will take a while - a workday or an overnight sleep are good time blocks to let that rice cool. It needs to be room temperature for you to add the koji, or else the heat will kill your koji! While you wait, acclimate your koji by pouring your 200 g of koji into a CLEAN quart jar full of clean, room-temperature water.
The next day (or when you get home from work or whatever) add that koji-water to your crock. Stir it well with a clean paddle, spoon, or spatula.
Let this sit for 24-48 hours. What's happening inside the crock is the koji is coming to life and fermenting the starches. Unlike most fermentators, koji turns starch into sugar (not alcohol or acid) - and you're going to soon turn that sugar into alcohol! The more you let your koji go wild, the more sugar you create and the more alcohol you'll have, but be wary - the process also creates earthy, sour notes that can contribute to flavor you may not like.
However long you let this process go, don't do it more than 48 hours. The koji will doubtlessly have done all they can after 48 hours. So, about 4-8 hours before you're ready to get this thing boozy, take your champagne yeast and add it to another room temperature quart of clean water - we use champagne yeast because they're hardy, give it a good bready flavor, and can survive in a good range of pH levels.
After that 4-8 hours is over, add your yeast water to the mix. Stir it again.
Now, a word on your fermentation vessel. For a short term ferment like this it's best to have a wide-mouthed barrel-or-bucket style vessel. A fermentation crock for sauerkraut works, a butter churn can work, and primary fermenters for starting beers can work. It's best not to do it in plastic - but it won't hurt, either. If you use a plastic fermentation vessel, just don't leave your rice in there too long - five days at max - it can soak up some plastic flavors.
So now you let it sit somewhere at room temperature as long as you'd like. The longer it sits, the more alcoholic it gets and the more sour it becomes. After about 10-12 days, you'll wind up with something that tastes like alcohol and yogurt, which isn't the greatest flavor. Shorter ferments are going to be weaker and sweeter, longer ferments will develop strength and sourness. Five days is the minimum you'll want to go for. Any less than that, it's going to be barely alcoholic amazake. Shoot for 7 days.
Now, the bottling. Pour your sake out through a colander and into a large bowl or container that will allow you to pour it into a bottle with a funnel or with a cup that has a spout, like a large measuring cup.
Whatever bottle you want, make sure it's clean - sterile if possible, this is easy to accomplish by pouring boiling water into your bottle then pouring it out, be incredibly careful there, though. Wine bottles are nice, it a bit big, beer bottles are good, go for the swing-top bottles either way, as you'll be opening/reopening/closing the bottles.
Keep it refrigerated. Drink it how you want. Drinking it warm will lead to more alcohol flavors and less of the earthy and sour notes. Drinking it cold will focus the sour notes.
Get out there and enjoy! And save me some.