Abstract: A method for cooking a food product under vacuum at low temperature includes placing a food product under vacuum in a sealed device and heating the product placed in the sealed device by submerging it in a bath in order to reach a target temperature of between 45° C. and 65° C., wherein the device comprises at least one thermochromic indicator configured to change color and/or appearance at the target temperature, and wherein the temperature of the bath is gradually raised from an initial temperature of at least 20° C. below the target temperature. A device for cooking a food product includes an envelope configured to contain the food product under vacuum and at least one thermochromic indicator in contact with the envelope.