In a small pot, bring 2 cups of water to boil. Turn off heat and add 1 tsp tea and 3 tbsp sugar, stir and let cool completely (place in a sink filled with cold water to speed things up).
In a quart glass jar, pour previously made tea discarding the leaves (use a mesh strainer) and 1 cup of store-bought kombucha along with any brownish strands from the bottle.
Cover with paper towel secured with a rubber band and set away from direct sunlight spot(counter or pantry) with temperature above 21C or 70F. It takes 2-4 weeks to grow a SCOBY. You can look but try not to disturb the jar as SCOBY is forming on top. See my post for video and pictures what SCOBY should look like and troubleshooting.
SCOBY is ready when it is at least 1/4″ thick and white in colour – a jellyfish like mushroom you can take out of the jar and hold in your hands.