I want to make broccoli cheddar soup tonight and it says to blend the stuff after you add the broccoli. I have a blender but it sucks and would rather use my ninja. Can I put hot liquids in this? How do I deal with venting the steam?
Typically, when blending hot soup:
This is one application where I believe an immersion blender (sometimes called a stick blender) is far superior, unless you are looking for an ultra-smooth soup (in which case you could also strain after blending). It is much easier to blend the soup in its pot than to transfer it batch by batch into the carafe of a traditional blender.
Agree with @SAJ14SAJ, especially his not suggesting that a good immersion blender might be a better idea.
However, just to add I also have the Ninja Prep (I assume you are talking about the Ninja Master Prep as you mentioned "processor" and not their various blenders) and recently had the exact same question. Specifically referring to the Ninja Prep, it is designed to be able to support Hot liquids. Directly from their FAQ:
The note about not being able to create hot soup refers to the fact that their actual blenders and other popular blenders (blentec, vitamix) advertise being able to actual create soup just using the blender.
On a practical note, I have used mine to blend soup. I made sure to limit the amount of liquid I added (probably about half the container?). You'll have to play around to see what works for you. Just don't fill it to the top as hot soup leaking out isn't fun. My best results came from adding only the solid bits from my soup, fished out with a strainer (in your case the broccoli) and only added enough liquid to keep it working. It won't create a perfect restaurant quality puree from fibrous vegetables, but worked more than well enough for my own use. For venting steam, I just pulsed a bit, and then opened the little pour spout occasionally and then I didn't have any issues.
For most cases I'd probably just stick to my stick blender. My main reason for using it over my stick blender was that my pot was deeper than my stick blender would go. Normally I don't make such large quantities that require blending.
In case you're actually referring to their blenders, then I would definitly not see an issue.