Start with whole garlic bulbs that are firm and unpeeled
Leave the outer skins intact
Place the bulbs in a rice cooker, slow cooker, or fermentation device
Keep the temperature low and steady, around 140–170°F
Maintain the heat for 2 to 4 weeks
Check occasionally to ensure the garlic is not drying out or burning
Allow the garlic to age until the cloves turn black and soft
Remove the bulbs and let them cool completely
Store the black garlic in an airtight container in a cool, dry place