Bring a medium pot of water to a boil. Add tapioca pearls and reduce heat to a simmer. Allow to simmer, stirring frequently until pearls are tender and transparent (25-30 minutes).
Combine coffee and brown sugar an mix until sugar is dissolved
Strain and rinse tapioca pearls with cold water. Add pearls to coffee mixture and stir until pearls are evenly coated with liquid. Cover the bowl and allow to chill in the refrigerator for at least 30 minutes.
When serving, divide pearls between 4 bowls, top with a dollop of yogurt