We have found the best way is to clean it after each use with a tidy tip. Also, running the temperature at the lowest you like will also allow the oils to not burn and cleanout easier.
Next, we recommend you can add a few drops of water to the dish when hot and then use a Tidy tip to clean it out.
If you have failed at maintaining the cleanliness and it is looking dark you can
remove the dish and let sit in alcohol for a day. You may need to scrap it some and add some salt.
You can also use a torch after you have removed most of the burnt oils and debris from the dish. Using a torch to clean the dish can cause it to get “Chazed” if it is too dirty and you get it too red hot. Just get it hot enough that the black starts to burn off, when clear you are done. No need to get it red hot.