An infuser having a non-porous region to selectively stop infusion. The infuser may be used in a vessel, such as a portable beverage mug suitable for preparing and drinking tea and other beverages. Methods for infusing contents (such as coffee or tea) into a beverage with the ability to stop the infusion process on command, and without having to remove the contents from the container or vessel holding the infuser. Once the beverage has reached a desired flavor, the flavoring ingredients can be pushed into the non-porous section of the infuser by pushing a press head to move the infusing contents into the non-porous region.