I brew a loose-leaf jasmine green tea. Since OP you are located in California, Chinese grocery markets are easy to come by, and most if not all of them carry this jasmine tea in a metal box. Bigger supermarkets also carry black tea, bricked tea, other fermented tea, but those are better served hot in tiny cups.
For the jasmine green, brew and filter it just like coffee, add in sugar (I prefer very small amounts of it, sometimes none at all, to preserve the taste of jasmine flower), then freeze and bottle. This tea works the same way as coffee, in that you only need to make enough tea for one day, and you do not want to drink leftover tea from yesterday.
Japanese stores also have their matcha and genmai green tea that taste very uniquely different. Whether they fit you or not, you need to be there and taste for yourself.
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