A container of sheet plastic reveals when it has been opened after a clerk loaded it with food. The container has a base (12) and lid (14) that remain latched together until they are separated at an initial opening region (40) where the lid has a radially-outward projecting lid tab (44) and the base has a tear-away part (52) with a blocker (60) that blocks access to the lid tab. The blocker surrounds the radially outward edge and opposite sides of the tab. The blocker prevents access to the lid tab to lift it to open the container until the tear-away part (52) is torn along a tear line (81). The fact that the tear-away part is torn away, reveals that the container has been tampered with.