Add water to a sauce pan. Bring to a boil, then add tapioca boba. Cook 30 minutes, stirring constantly. (Cooking time will vary depending on the type of boba you get - check directions on package.)
Turn off the heat. Pour boba through a strainer into a bowl. Add lavender simple syrup. Let marinate 15-20 minutes.
Tea
Add water to a saucepan. Bring to a boil. Remove from the heat and add tea bag. Let steep 5-7 minutes.
For Serving
Scoop ¼ cup tapioca boba into a glass. Top with tea, soy milk, and a little lavender simple syrup, if desired.
Notes
If you don't use all the cooked boba, store it in the lavender simple syrup mixture for up to 3 days. The lavender bubble tea will last 24 hours in the fridge.