Abstract: The invention is a valve for a microwavable container having a flexible lid. The valve has two posts extending from one side of a body member, and the posts correspond to two apertures in the lid. The cross-sectional area of the posts are larger than the apertures in the lid, and the distal portions of the posts are larger than the proximal portions. When the posts are engaged with the apertures a liquid-tight seal is formed. One post can be removed from its corresponding aperture to create a vent for microwave cooking, while the other post remains engaged with the lid to anchor the valve to the lid. The body portion of the valve extends beyond the vent post and preferably flares upwardly and fans laterally to form a tab to facilitate opening of the vent. The body portion also preferably has a thin between the posts in a direction substantially perpendicular to the line of the posts to facilitate hinging of the valve.