A disposable mixing system includes a lid having an opening and configured to hold contents within a container, a strainer configured to couple with the container and the lid in a position between the container and the lid, where the strainer mixes the contents responsive to shaking the container, and a cap configured to cover the opening of the lid, where at least the lid and the strainer are formed in a unified piece. The system may be manufactured from a single sheet of plastic using thermoforming. The strainer may use flat surfaces and large triangular orifices for efficient mixing and manufacture, while the lid may have a spout sized to prevent clogging and pressure build-up.