Add the Kefir Soda Starter packet OR kefir whey to your juice and stir till dissolved. Fill the rest of the bottle with water leaving 2 inches of room at the top. Add the mulling spice tea bag last and it will float at the top so you can remove it when you are done fermenting. Be careful pulling the tea bag out. It can rip and tear open.
Allow it to ferment for 3-7 days or until bubbly and fizzy. If your home is 75°F or warmer it will usually take 3-4 days. Colder homes can take 5 days or longer, but you'll need to check it by popping the top to see if it's getting fizzy. It will start to bubble out the top if it does.
When it's done, you can pour into a glass and enjoy right away or place it in the fridge. Keep it stored in the fridge or it will continue to ferment and get overly fizzy and hard to pour. Burp daily and consume within 1-2 weeks for the best flavor and most benefits.
You can use ½ cup of this finished kefir soda as a starter to make a new bottle.Add the other ingredients and ferment again. It should only take a half to a full day to ferment. It ferments faster on subsequent batches and you can make many bottles over and over again!