A temperature controlled food service container is formed with an inner portion having side walls and an opening for the receipt of food, and an outer portion having sidewalls spaced from the inner portion with a eutectic gel, disposed between them. A ledge extends from the periphery of the outer portion with a flange extending from the inner portion seated against the ledge; and is held by an ultrasonic bond joining the ledge to the flange. The food container has ribs along the sidewalls of the inner and outer portions. Peripheral channels and ridges are formed respectively on the ledge and flange for welded engagement with each other, the channels having enlarged segments which extend beyond the cross-sectional dimension of a respective ridge received therein. The method for making the food service container includes molding an outer walled shell portion having a ledge with at least one peripheral channel, and molding an inner walled shall portion having a major peripheral flange with at least one peripheral protuberance. Thereafter a eutectic gel is placed into the outer walled shell portion and the inner walled shell portion is placed therein. The peripheral protuberance is indexed into the peripheral channel and the ledge and flange are ultrasonically bonded.