The invention relates to a portable hand-held device for accommodating and transporting food or a beverage, having a thermally insulated container (2), which is intended to accommodate food or a beverage in an accommodating space (7) and which has an inner and an outer wall (8), and an insulating space (9) arranged therebetween, enclosing the accommodating space, the insulating space being of closed and sealed design and having been evacuated; and having a container closure (3), which is intended to close a container opening (4) of the thermally insulated container (2), wherein the insulating space (9) contains a working medium (11) which, by means of thermal energy being supplied from the outside via the outer wall (8), can be transferred in a reversible manner between a thermally insulating, initial state, in which the working medium (11) is in the solid state and is in contact with the outer wall (6), and is not in contact with the inner wall (5), and a thermally conductive state, in which at least some of the working medium (11) is in the liquid state and has expanded and is in thermally conductive contact both with the outer wall (6) and with the inner wall (5). The invention also provides a method for controlling the temperature of food or of a beverage in a portable hand-held device.