Fermented Hot Sauce & Peanut Rayu

Recipe: Fermented Hot Sauce & Peanut Rayu

Two things we nearly always have in our fridge at Cow House are a fermented hot sauce and peanut rayu. These two condiments are seriously addictive and seem to work on just about everything. During our residencies and our summer program, we’ve noticed that some people pull them out at almost every meal. During the spring session of our 2019 gap year, a few of our students used so much of the fermented hot sauce Caitriona could barely keep up. The peanut rayu is equally delicious, and although these two condiments share in their bit of heat, they’re quite different.

The peanut rayu, inspired by Katie Sanderson’s tasty creation, balances spice from the dried chili with sugar and tamari, crunch from the peanuts and the sesame seeds, all in a rich oily base. The fermented hot sauce, pulled from the Sullivan Street Bakery cookbook, is bright, salty and acidic. It’s not as hot as it might seem, considering it consists almost entirely of chopped chilies. The fermentation process seems to mellow out the spice.

Caitriona has been into fermentation for a few years now, making kombucha, kimchi, and sauerkraut. The hot sauce was among her first successful experiments and has been a mainstay. Frank bought a jar of the peanut rayu from White Mausu about a year ago and, after several tests, landed on the version shared here. These two condiments work particularly well on our rice bowls and with our Hainan Chicken Rice, but a teaspoon of peanut rayu on a couple of fried eggs in the morning or a dollop of fermented hot sauce on one of our BLT’s are both pretty great.

Peanut Rayu: Ingredients

  • 250g Peanuts (We use red-skinned)

  • 5 cloves of garlic; Thinly sliced

  • 500ml rapeseed oil

  • 125g Korean red chili powder

  • 65g sesame seeds

  • 65g Tamari

  • 65g Sugar

  • 100g toasted sesame oil


Preheat your oven to 200° Celcius and roast the peanuts with a few pinches of salt until they start to sweat. Remove from the oven and cool to room temperature.

The following day, heat the rapeseed oil to 180° Celcius and add the garlic. Fry until it appears lightly browned, then remove the crisped slices from the oil with a strainer. Place the garlic onto kitchen roll to drain the oil. Reserve the oil used to fry the garlic and allow it to cool for about ten minutes. You’re looking for it to cool to about 120° Celcius.

In a bowl, mix the Korean red chili powder and sesame seeds. When the oil has cooled, slowly pour it over the Korean red chili powder and sesame seed mixture, stirring until it’s well incorporated. In a small bowl, combine the tamari, sugar, and sesame oil. Once dissolved add this mixture to the oil, chili, and sesame seeds.

Finally, add in the toasted garlic and peanuts then season to taste. Allow the peanut rayu to cool completely for about 1 hour, and then transfer the finished condiment to jars for storing.

Fermented Hot Sauce: Ingredients

  • 1kg fresh red chilies. ( the type of chilies you use will determine the spice level)

  • 33gs sea salt

  • 10g peeled ginger

  • 1 garlic clove.


Chop the stems off the chilies. If you prefer a little less spice, you can remove the seeds and the white stems. We leave ours in when we make it at Cow House. Place the chilies and the rest of the ingredients into a food processor. Blitz for a few seconds chopping everything together, taking care not to over blitz everything into a liquid, you want the chilies to look finely diced. You may need to do this in a few batches.

Transfer the mix into a one-liter glass jar, and weigh down the chilies with a fermentation weight. The salt will release the liquid from the chilies, and the pressure from the weight will help the liquid rise to the top, preventing oxygen from getting into the sauce.

Cover the jar and leave it out at room temperature for two to five days. Time can vary depending on the heat of your kitchen. During colder months, we need to give the chili sauce the full five days, and during the summer, two days is usually sufficient.

You can tell the fermentation is done when you see bubbles forming and rising to the top. You should check the sauce every day to ensure it is fully submerged in liquid and release pressure from the jar, opening and quickly closing the lid does the trick.

Once done, place it into the fridge. The colder temperature will slow down the fermentation process, and the sauce keeps well in the refrigerator for a few months.

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