Bring a large pot of water to a simmer over medium heat. Add the tapioca balls and cook, uncovered, for 40 minutes, stirring occasionally so they don’t stick to the bottom or sides of the pot. Remove the pot from the heat, cover with a lid, and let sit for 30 minutes. (If you prefer softer pearls, cook for 45 minutes and let rest for 35 minutes.)
Drain the pearls. Transfer to a medium bowl of cold water and let sit until you are ready to serve, up to 2 hours.
Drain the tapioca pearls. Sprinkle the brown sugar into a large pot. Stir over medium heat for 2 to 3 minutes, until the sugar starts to dissolve, making sure the sugar doesn’t burn. Add the boba pearls and stir for another 2 to 3 minutes, until the glaze is thick and every pearl is completely coated. Remove from the heat.
Heat the milk in a medium saucepan over medium heat. Once the milk starts to simmer, add the tea bags and gently stir for 2 to 3 minutes, depending how strong you like your milk tea. Remove from the heat. Discard the tea bags and let the milk cool for 10 minutes.
Spoon about ¼ cup of boba pearls into each of two large glasses. Fill with ice cubes, then add the milk tea. Serve with a wide straw.