Method for controlling the operation of a food preparation device, said food preparation device comprising: - a casing, - a tank mounted on the casing and arranged to receive food to be prepared, - at least one working mobile member disposed in the tank and arranged to work the food received in the tank, - a stirring motor disposed in the casing, and arranged to displace the working mobile member, - a removable cover arranged to give the tank a closed state wherein the tank is closed by the cover, - means for locking the cover on the tank, the cover being arranged to be able to be displaced when the tank is in its closed state between: - an unlocked position on the tank, wherein the cover is removed from the locking means, and - a locked position on the tank, wherein the cover engages with the locking means, - preferably heating means arranged to provide heat for cooking the food received in the tank, - means for securing the locking of the cover in locked position, comprising: - at least one mobile blocking member between a first position wherein the displacement of the cover from the locked position to the unlocked position is enabled, and a second position wherein the blocking member impedes the displacement of the cover from the locked position to the unlocked position, - a geared motor arranged to act on the blocking member so as to allow it to be displaced between its first position and its second position, the control method comprising steps of: - estimating a parameter representative of a torque provided by the geared motor during a control of the geared motor, - comparing the estimation of said parameter with a predetermined threshold, and - prohibiting the operation of the stirring motor and/or heating means as the estimation of said parameter during a control of the means for securing locking remains less than the predetermined threshold in a time interval comprised between a minimum displacement time (Tm) and a predetermined maximum displacement time, counted from the generation of a geared-motor control signal. - a casing, - a tank mounted on the casing and arranged to receive food to be prepared, - at least one working mobile member disposed in the tank and arranged to work the food received in the tank, - a stirring motor disposed in the casing, and arranged to displace the working mobile member, - a removable cover arranged to give the tank a closed state wherein the tank is closed by the cover, - means for locking the cover on the tank, the cover being arranged to be able to be displaced when the tank is in its closed state between: - an unlocked position on the tank, wherein the cover is removed from the locking means, and - a locked position on the tank, wherein the cover engages with the locking means, - an unlocked position on the tank, wherein the cover is removed from the locking means, and - a locked position on the tank, wherein the cover engages with the locking means, - preferably heating means arranged to provide heat for cooking the food received in the tank, - means for securing the locking of the cover in locked position, comprising: - at least one mobile blocking member between a first position wherein the displacement of the cover from the locked position to the unlocked position is enabled, and a second position wherein the blocking member impedes the displacement of the cover from the locked position to the unlocked position, - a geared motor arranged to act on the blocking member so as to allow it to be displaced between its first position and its second position, - at least one mobile blocking member between a first position wherein the displacement of the cover from the locked position to the unlocked position is enabled, and a second position wherein the blocking member impedes the displacement of the cover from the locked position to the unlocked position, - a geared motor arranged to act on the blocking member so as to allow it to be displaced between its first position and its second position, - estimating a parameter representative of a torque provided by the geared motor during a control of the geared motor, - comparing the estimation of said parameter with a predetermined threshold, and - prohibiting the operation of the stirring motor and/or heating means as the estimation of said parameter during a control of the means for securing locking remains less than the predetermined threshold in a time interval comprised between a minimum displacement time (Tm) and a predetermined maximum displacement time, counted from the generation of a geared-motor control signal.