How To Make Yuzu Kosho Citrus Paste

What Is Yuzu Kosho?

Yuzu kosho is a Japanese condiment using fresh yuzu zest to make a salty citrus chili paste. Yuzu is a Japanese citrus, with hints of both lemon and lime.  Green yuzu is traditionally used to zest the skin and once the yuzu turns yellow when ripe, it can be juiced.  Yuzu is a fundamental flavor in Japanese cuisine and it adds beautiful citrusy acid to any dish!

When making kosho, you don't need to limit yourself to yuzu - because you can use whatever citrus and peppers are available!  We have beautiful koshos in ferment using grapefruit, meyer lemon, mandarin, naval orange, kaffir, togarashi peppers, green chili peppers, gochu chili, rainforest chili, serrano, dragon claw peppers, jigsaw peppers and many more.

Yuzu Kosho is a lesser-known ferment – but it is one of the true secret weapons in building flavors.  At Suis Generis, we often use our house made koshos to add a salty spicy & citrus forward accent to a wide range of dishes.  We encourage people to think outside the box when building a dish.  There is no reason to bind yourself to a specific “region” or style of cooking.  Instead, open your mind to the possibilities of flavor diversity.  So put a little kosho in your tartar sauce, mac & cheese or marinade to ramp up the flavors.

Complexity and intrigue is a good goal when cooking.  If your dish tastes flat, the answer is very often acid, such as citrus or vinegar.  Textural differential is also important, because it makes the dish “eat” differently as you progress through the meal.  One of my favorite pieces of advice is, you have accomplished something if your guests can take multiple paths in how they eat through the dish.  That subtle playfulness is what elevated food is all about.

Kosho can be your answer to building intrigue and layering flavors.  The ingredients in kosho are simple: citrus zest, peppers and salt.  However the range of types of zest, peppers, and salt is only limited by your imagination and availability of product.  This is why we created the SG Tiki Farm – because we want to push the limits of creativity and flavor variability without limit.

You can also add other ingredients to your Kosho.  For example we recently started a kosho ferment with delicious Tiki Farm ingredients, including Brazilian rainforest chili peppers, rose petals, and a range of citrus zested from fruit that we squeezed for bar juices.  The floral undertones taste amazing already and fermentation has only started!  You can also add koji to kosho for another layer of umami richness.  When adding additional ingredients, the key is to weigh all ingredients together before calculating your salt amount.

How To Make Kosho

Here is the basic recipe:

·       One part citrus zest

·       One part minced fresh peppers

·       5-10% salt

The traditional method of getting zest is to cut the citrus in half and scrape out all of the pulp and white rind, leaving just the colored outer skin.  With this method, you maximize your amount of zest.  However, at Suis Generis and the Tiki Food Lab, we seek to achieve zero waste, so our most common approach is to use a microplane to zest fruit before it is squeezed. 

Regarding peppers, feel free to experiment with hot peppers, sweet peppers, medium peppers, and mixes of all of those.  Because kosho maintains beautiful color even after it ferments, its fun to make koshos with every color of the rainbow!

Salt is your partner in fermentation and wards off bad bacteria.  Never use iodized salt because it contains iodine which inhibits beneficial fermentation.  As with any recipe, the end result is the sum of its parts.  Thus, always use the best natural salt when fermenting, such as French grey salt,  Himalayan Pink salt, Hawiian alaea salt, fleur de sil, or Japanese Moshio salt.  Regular unrefined sea salt is also fine.

To make kosho, run your peppers and zest through a food processor to mince.  Then weigh your mixture and add between 5 and 10% salt.  The amount of salt depends on the temperature you will hold your ferment, how long you plan to ferment it, your confidence in fermentation, and how salty you want your end product to be.  We find that 8% salt is a good amount for long ferments in warm temperatures, like we have in the Tiki Food Lab.  If your house is 68 degrees, then you can stick to the 5-6% range. 

Finely, mix your kosho well and pack it into a glass jar.  Then use a piece of cellophane cut to size and press it to the surface and up to the sides of your container.  We call this a “raft” and it helps minimize direct oxygen contact, which further promotes beneficial fermentation.  Next, you can either cover the top with cheesecloth and affix it in place with a rubber band or screw on the lid.  Either way is fine and we find that fermentation tends to accelerate with the cheesecloth cover and access to air.  In either case, you should stir it every few months and replace your raft.  You can also sprinkle a bit of salt on the surface before affixing your raft if you want some extra protection.  However, kosho is a high salt content ferment so it is very rare that kosho goes wrong.  You can continue fermenting kosho for years without refrigeration - but its a good practice to continue stirring it every few months.  Or, put it in the fridge when you like the flavor and it will last a very long time.

We always tell people to trust your nose when fermenting.  Good ferments smell great – even fish sauce!  So, if your ferment does not smell right, it’s a good idea not to trust it.  However, we have never had a batch of kosho go wrong…so, don’t be scared, and jump in there and ferment!!!!