The usage of purple casserole is as follows: 1. Before using the purple casserole, soak the purple casserole in clear water for at least 10 hour to make it fully absorb water, make the purple casserole swell and eliminate internal cracks, so as to ensure the safety of use. 2. Put the purple casserole soaked in water into boiling water, stir the boiling water regularly, so that the temperature of the purple casserole rises to about 100℃, and then put the purple casserole into cold water and cool it to below 50℃. 3. Put the purple casserole into cold water, add meat, vegetables and other ingredients, and cook with medium and small fire to avoid the purple casserole from being damaged by heating too fast. In this process, you can add proper amount of cooking oil and salt to enhance the taste of food. 4. After the purple casserole is cooked, it should be immediately cooled in cold water to prevent the purple casserole from being damaged due to excessive heating. After cooling, it can be washed with clean water and then soaked in warm water to eliminate residual oil stains.