1 Tbsp culture (optional, see section above for details)
Soak the millet in 2 cups of water for 24 hours. This will soften the millet and start the fermentation process.
Drain the water from the millet, then grind it into a smooth paste.
Mix the millet paste with 1 cup of water and put it in a glass bowl or jar for fermenting. You can add 1 Tbsp of culture at this point, but it isn’t required (see the section above for details). Cover with a tea towel and leave the millet to ferment in a warm location for 2-3 days. Stir at least once a day. After a few days, it will bubble and start to smell sour.
To cook fermented millet porridge, scrape the millet paste and fermentation liquid into a pot. Mix with an additional 2 1/2 cups of water. Slowly bring to a simmer and cook for 15-20 minutes, stirring frequently. It will be very soft and creamy, with an almost gel-like consistency, when finished.