A container for a food product generally includes a tray and a cover attached to the tray by ultrasonic bonds. The tray includes a bottom having a perimeter and a sidewall extending along the perimeter of the bottom to form a cavity sized to receive the food product. The sidewall defines an opening for the food product to be placed into the cavity. The tray also includes a flange extending from an edge of the sidewall and around the opening. The flange has a single layer first area with a first thickness and a second area comprised of at least two layers with a second thickness. The second thickness is at least twice as thick as the first thickness. The ultrasonic bonds extend along the entire sidewall of the container to form a continuous, hermetic seal between the cover and the tray around the opening.