How to show toast in AsyncTask in doInBackground

In one of my activities I'm using AsyncTask. In doInBackground() I'm making calls to various methods. In one of these methods I'm getting an exception, so in the catch block I want to show the error in the Toast. I know I can use Log, but still I prefer Toast. So, how can I use Toast in AsyncTask in doInBackground()?

return from doInBackground as

protected String doInBackground(String... params){
    //some code
    try{
       //some code
     }catch(Exception e){
        return "Exception Caught";
     }
     return someValidResult;
}

protected void onPostExecute(String result){
    if(result.equalsIgnoreCase("Exception Caught")){
       //Display Toast
    }else{
       // // whatever you wana do with valid result
    }
}

You could wrap the Toast in runOnUIThread() but this isn't the best solution.
You should set a boolean flag in the catch block when an error occurs, then display an appropriate Toast in onProgressUpdate(), onPostExecute(), or any of the other methods with UI access whenever the flag is true.