Mossy Life

Shio Koji (Salt Koji)

Shio koji is a Japanese fermented seasoning made from rice koji, salt, and water. It's incredibly versatile - use it to marinate fish, chicken, pork, or vegetables. The koji enzymes break down proteins and add umami depth to whatever you're cooking.

Recipe Credit

This recipe is from Sonoko Sakai and her excellent book Rice Craft: Wafu Cooking. If you're interested in Japanese fermentation and rice-based cooking, her book is essential.

Ingredients

For a 20oz batch:

• 567g (20oz) freeze-dried rice koji
• 200g (~13 tablespoons) sea salt
• 800ml (~3⅓ cups) warm water at 80-90°F (26-32°C)

Yield: About 4-5 cups of shio koji

Equipment

• Large glass or ceramic bowl
• Clean kitchen towel
• Storage container with lid (glass jar or plastic container)
• Thermometer (optional but helpful)

Where to Buy Koji

In Portland, Uwajimaya carries freeze-dried rice koji in their refrigerated section. You can also find it at other Asian grocers or order online. Look for packages labeled "rice koji" or "rice malt" - it looks like broken rice grains with white fuzzy mold.

The Process

Step 1: Mix Koji and Salt

1. Break up the koji with your hands - it often clumps together
2. Put the koji in a large bowl
3. Add the salt
4. Mix thoroughly with your hands, breaking up any remaining clumps

Step 2: Add Warm Water

1. Heat water to 80-90°F (26-32°C) - it should feel warm but not hot to the touch
2. Pour the warm water over the koji-salt mixture
3. Stir well to combine
4. All the koji should be submerged in liquid

Step 3: Ferment

1. Cover the bowl with a clean kitchen towel
2. Leave at room temperature (65-75°F) for 2-3 days
3. Stir once a day
4. It's ready when the koji grains are soft and the mixture smells sweet and slightly funky (in a good way)

Step 4: Store

1. Transfer to a clean container with a lid
2. Store in the refrigerator
3. Keeps for 6+ months refrigerated

How to Use Shio Koji

For Marinades

Use about 10% shio koji by weight of whatever you're marinating:

• Fish: Marinate for 20-30 minutes (salmon, mackerel, sea bass)
• Chicken: Marinate for 2-4 hours or overnight (thighs, breasts, whole birds)
• Pork: Marinate for 2-4 hours or overnight (chops, tenderloin, belly)
• Vegetables: Marinate for 1-2 hours (eggplant, mushrooms, root vegetables)

Example: For 500g (about 1 lb) of chicken, use about 50g (3-4 tablespoons) of shio koji. Coat the meat, let it sit in the fridge, then cook as normal. You'll get tender, flavorful results.

Cooking Tips

• Wipe off excess shio koji before cooking (it can burn)
• The sugars from the koji caramelize beautifully when grilled or pan-fried
• Reduce seasoning in your dish - shio koji is salty
• Works great for yakiniku (grilled meat) or simple pan-seared fish

Storage

• Refrigerator: 6+ months in a sealed container
• Freezer: 1+ year (fermentation stops when frozen)

The shio koji will continue to slowly ferment in the fridge, which is fine. It will get a bit funkier over time, but that's normal.

Why Make This?

1. It transforms meat and fish. The enzymes tenderize protein and add incredible depth of flavor.
2. It's simple. Three ingredients, minimal effort, and you have a fermented seasoning that lasts months.
3. It's versatile. Use it on anything you'd normally salt - but with more complexity.
4. Store-bought is expensive. A small jar of prepared shio koji costs $8-12. Making your own costs about $2-3.

Once you have shio koji in your fridge, you'll start using it regularly. Chicken thighs marinated in shio koji and grilled are delicious. Salmon with shio koji turns out perfect every time.