Is it possible to use an async action within an Umbraco SurfaceController (and UmbracoApiController)

I tried the following code

public async Task< ActionResult> HandleLogin(LoginViewModel model)
{
    await Task.Delay(1000);
    return PartialView("Login", model);
}

and although it compiled correctly when the action is called the action seems to return as soon as the await is hit, and returns a string

System.Threading.Tasks.Task`1[System.Web.Mvc.ActionResult]

the controller of course inherits from SurfaceController and I wonder if this is the problem?

If this is not possible, are there any workarounds to achieve async action behaviour?