Infusion beverage brewing system

An infusion beverage brewing system includes a container and an infuser. The infuser is positioned in a liquid, such as hot water, and has an infusing chamber for containing infusible materials, such as tea leaves. A plunger includes a piston with a peripheral seal and flap valves. After a brewing time has elapsed, an individual pushes on an operator to move the piston past a perforated wall portion of the infusing chamber. When the piston reaches a solid wall portion at the bottom of the infusing chamber, the flap valves open to allow liquid to escape. However, small apertures aligned with the flap valves prevent the passage of the infusible material. Consequently the infusible material is isolated from the liquid when the piston reaches a solid bottom wall portion of the infusing chamber.