The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
In Chinese Medicine sunburn can be treated by one herbs that we have on record. Here is the list below.
Because it is a herb specifically indicated to treat sunburn as can be seen on Bletilla Rhizome's page.
Its main actions are: Stops bleeding in the Stomach and the Lungs such as coughing with blood or ulcers. Also stops bleeding or inflammation due to traumatic injury. It can also heal sunburned skin or chronic sores that don't recover easily.