Brew 4 cups of water
Add 1/4 cup sugar
Bring to a boil and stir until the sugar dissolves
Remove from heat
Add 2 black tea bags or 2 teaspoons loose black tea
Steep for 10 to 15 minutes
Remove the tea bags or strain out the tea leaves
Let the sweet tea cool to room temperature
Pour the cooled tea into a clean glass jar
Add 1/2 cup plain unflavored store-bought kombucha with live cultures
Cover the jar with a breathable cloth or coffee filter
Secure the cover with a rubber band
Keep the jar in a warm, dark place
Leave it undisturbed for 7 to 14 days
Check for a new SCOBY forming on the surface
Wait until the SCOBY is about 1/4 inch thick
Remove the SCOBY with clean hands or utensils
Store it in a little starter liquid if not using immediately