The invention relates to a method for wrapping and sealing a flexible sheet over an insert (10) to produce a pack (100) for preparing a food or beverage product from one or more ingredients; the pack comprising an insert (10) and a container (20) made from the flexible sheet folded to store the one or more ingredients, the flexible sheet being arranged overwrapping and matching the shape of the insert (10) in its entirety except for the part of the insert (10) in direct communication with the inner volume of the container (20); the method comprising the following steps: —holding the insert (10) so that it is substantially perpendicular with respect to the flexible sheet; —moving the insert (10) towards the flexible sheet, until it touches a bottom sealing tool (210); —moving at least two side sealing tools (220, 230) towards the insert (10); —applying by the bottom sealing tool (210) and by the side sealing tools (220, 230) a certain required pressure and temperature to achieve a tight sealing of the flexible sheet over the entirety of the insert (10) except for the part of it in direct communication with the inner volume of the container (20). The invention further relates to a device (200) for wrapping and sealing a flexible sheet over an insert (10) to produce a pack (100) for preparing a food or beverage product from one or more ingredients.