Make the boba pearls: Place the 1¼ cups tapioca starch in a large heatproof bowl. In a small saucepan, combine the water and brown sugar. Heat over medium heat, stirring occasionally, until the sugar is dissolved. Pour the mixture over the tapioca starch and stir quickly with a pair of chopsticks. The dough will be very sticky. Let sit until cool enough to handle.

Knead the dough in the bowl until it forms a smooth ball. Cover with a damp kitchen towel and let sit for 15 minutes.

Transfer the dough to a floured work surface. Cut into four equal portions. Working with one portion at a time, roll the dough into a ¼-inch-thick rope. Cut the rope crosswise into ¼-inch pieces. You can adjust the size depending on how big you prefer your pearls to be. The pearls will expand when cooked.

Put about ½ cup of tapioca starch in a medium bowl. Using your hands, roll each piece of dough into a ball and place in the starch. Coat the balls with the tapioca starch to prevent them from sticking to each other. At this stage you can freeze the balls in an airtight container for up to 1 month.

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.

When ready to serve, make the brown sugar glaze: 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.

Make the milk tea: 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.

Assemble the boba milk tea: 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.