Naio wrote:
The windows in the van do not fog up.
Well that proves that steam venting into the air is NOT the problem......because excess humidity will condense of single pane glass BEFORE anything else (well maybe except a thin piece of un-insulated metal).
If there is that much steam presenting itself in one place, the odds are great that you are boiling your food and hot liquid water is splashing out somewhere.
"Cooking" the food for a longer period on a lower power setting might solve the problem. Or maybe stopping the heating as soon as the steam appears and then letting it sit for a couple of minutes.