A container for the storage and dispensing of a liquid and which incorporates a sealing mechanism includes a blow-molded container body including a neck portion having a series of external threads and defining an annular, non-planar sealing surface, a pouring spout assembled into the body and a unitary closing lid including a series of internal threads constructed and arranged to engage the threads of the neck portion. The unitary closing lid includes the sealing mechanism in the form of a pair of annular sealing lips constructed and arranged to be compressed against the annular, non-planar sealing surface to establish a sealed interface between the closing lid and the body.