In this case, my recommendation for ironing is to make the top of the “strainer” surface as smooth as possible. So “Top surfaces” would be the best option. FYI: I did also experiment with using a very fine wet sandpaper to make it even smoother but I am not sure it made much difference so I won’t recommend it but it might be worth exploring more. I might make another design of it later with a difference strainer hole approach to see if that can help with the release of food waste from the surface.