Drain and rinse the cashews. Combine them in a high-speed blender along with the ½ cup filtered water and the powder from one probiotic (you can discard the gel-cap).
Once the mixture is smooth, transfer it to a covered ceramic bowl and either, 1) let sit on the counter for around 24 hours or until soured, or 2) place in a food dehydrator or yogurt maker on the lowest setting for 8-12 hours.
After the time has passed, taste for sourness. You can let it continue to sour for a few more hours, but I wouldn't let it go beyond 30 hours.
Next, combine the fermented cashew base with the turmeric, lemon juice, salt, garlic powder, yeast, and black pepper. Taste and adjust seasoning.
Chill for a few hours before serving. This spread should last in the fridge for around 5-7 days.