Add tea bags and remove from heat. Allow to steep 5-10 minutes. Remove tea bags.
Add sugar and stir to dissolve. If the sugar is taking too long to dissolve, turn on the heat again and heat 1-2 minutes to dissolve the sugar.
Add sweetened tea to a clean gallon-sized jar. Fill with room-temperature filtered water. Using a kitchen thermometer, make sure the tea is 75°-85°. (By adding room temperature water to the hot tea mixture it will be around 85°-87°, but it will cool down to room temperature.)
Add the kombucha culture and homemade kombucha (or starter tea culture and starter tea) to the sweetened tea. Secure a tea towel or coffee filter over the jar with a sturdy rubber band.
Place the jar in a warm area that is between 75°-85°. Cold temperatures cause mold, so a warm area is necessary for the success of your kombucha!
The kombucha will be ready between 7-21 days. Taste it at day 7. If it's too sweet, ferment it longer. I like to brew mine for 14-21 days depending on the season. Save 1-2 cups for the next batch and start another batch!
Notes
*If using a kombucha starter pack you won't need homemade kombucha because the starter culture comes in starter tea.I have not brewed with yerba mate over several batches, but I did some research and read that in order to maintain the kombuchastrain you'll want to use 25-50% yerba mate to black tea. You could also just make one to two batches with an extra scoby.To sweeten the yerba mate kombucha and make it bubbly, you will need some bottles with flip-top lids. I use 25 oz. bottles.Pour 2 tablespoons maple syrup, then the finished homemade kombucha into each bottle, leaving 1-2" head space. Let sit 3-5 days, popping the bottles each day to let out carbon dioxide. Taste each day to test its flavor and fizziness.