Manually-opened container , for example for fruit or vegetables, comprising: - a cardboard tray forming five sides and having, at the periphery of an open sixth side , external rims formed by at least one double fold of edges of the cardboard, the first fold line of the cardboard forming a support line for a lid and the second fold line of the cardboard closing off the edge of the cardboard between two surfaces of the cardboard, said rims being at least partially detached from the remainder of the tray's external surface at the corners of the tray, and, over two opposite sides, the rims are substantially triangular in a plane parallel to said sides and their size is smaller than the size of an edge junction between each said side and the open sixth side; and - a lid , made of plastic at least partially transparent to visible wavelengths, surrounding the sixth open side of the tray and having: . at least one shoulder to come and rest on the support line of the exterior rims of the tray; and . edges superimposed on the exterior rims of the tray and protruding beyond said rims of the tray, inward lugs being formed at the corners of the edges of the lid outside the rims of the tray for locking the lid onto the tray, wherein at least one lug of the lid comprises at least three non-parallel sides , whose projection on the edge fitted with said lug forms a right triangle such that the triangle's hypotenuse rests on one of the at least partially detached substantially triangular rims, one of the sides opposite the hypotenuse being parallel to the plane of the shoulder, the other side being perpendicular to the plane of the shoulder. - a cardboard tray forming five sides and having, at the periphery of an open sixth side , external rims formed by at least one double fold of edges of the cardboard, the first fold line of the cardboard forming a support line for a lid and the second fold line of the cardboard closing off the edge of the cardboard between two surfaces of the cardboard, said rims being at least partially detached from the remainder of the tray's external surface at the corners of the tray, and, over two opposite sides, the rims are substantially triangular in a plane parallel to said sides and their size is smaller than the size of an edge junction between each said side and the open sixth side; and - a lid , made of plastic at least partially transparent to visible wavelengths, surrounding the sixth open side of the tray and having: . at least one shoulder to come and rest on the support line of the exterior rims of the tray; and . edges superimposed on the exterior rims of the tray and protruding beyond said rims of the tray, inward lugs being formed at the corners of the edges of the lid outside the rims of the tray for locking the lid onto the tray, wherein at least one lug of the lid comprises at least three non-parallel sides , whose projection on the edge fitted with said lug forms a right triangle such that the triangle's hypotenuse rests on one of the at least partially detached substantially triangular rims, one of the sides opposite the hypotenuse being parallel to the plane of the shoulder, the other side being perpendicular to the plane of the shoulder. . at least one shoulder to come and rest on the support line of the exterior rims of the tray; and . edges superimposed on the exterior rims of the tray and protruding beyond said rims of the tray, inward lugs being formed at the corners of the edges of the lid outside the rims of the tray for locking the lid onto the tray, wherein at least one lug of the lid comprises at least three non-parallel sides , whose projection on the edge fitted with said lug forms a right triangle such that the triangle's hypotenuse rests on one of the at least partially detached substantially triangular rims, one of the sides opposite the hypotenuse being parallel to the plane of the shoulder, the other side being perpendicular to the plane of the shoulder. <EOS>