Essential oils can add a fascinating dimension of flavor to teas, adding a concentrated punch of aroma and taste without the bulk of fruits or dried herbs or spices. Consider using essential oil in your bottled tea formulations.
However, remember that not all essential oils are safe for consumption, so it's vital to stick to food-grade oils listed by FDA and/or FEMA as Generally Recognized as Safe for Human Consumption for culinary use, and follow FEMA safe-quantity guidelines in your formulations.