Unfortunately, I couldn't find an extant clip of the scene in question. The video here is a series of cut clips, edited down from the full episode to give the gist of the thing. If you notice when Batman kicks Mr. Freeze, the hemet doesn't break. When the scene cuts away to Freeze's exposed head, the steam you see is a direct result of hot soup on a cold head. That having been said, I highly recommend the full episode, one of B:TAS's best.