Preparation

This recipe bridges Japanese fermentation techniques with European butter-making traditions, creating something entirely new. The koji rice adds enzymatic depth while black garlic contributes sweet, tangy funkiness.

Making the Koji Rice

1. Steam the rice until fully cooked and spread on a sterilized tray to cool to 95°F (35°C).
2. Sprinkle koji spores evenly over the rice and mix thoroughly with clean hands.
3. Place in a humidity-controlled environment at 86-95°F for 48 hours, stirring every 12 hours.
4. The rice should smell sweet and slightly musty when ready; dry completely.

Assembling the Butter

1. Mash the black garlic cloves into a smooth paste using a mortar and pestle.
2. Grind the dried koji rice into a coarse powder using a spice grinder.
3. Mix butter, black garlic paste, miso, koji powder, salt, and vinegar until homogeneous.
4. Pack into a sterilized jar, leaving 1 inch headspace.
5. Cover with cheesecloth and secure with a rubber band.
6. Ferment at room temperature for 5-7 days, stirring daily.
7. Refrigerate and age for an additional 2 weeks before using.

The finished butter will have developed complex funky notes reminiscent of aged cheese and fermented soybeans. Use it to finish steaks, melt over roasted vegetables, or spread on crusty bread.