It turns out we can!
We tested it out tonight and were rewarded with a delicious treat.
Step 1: Fill jar with coarse salt and ice. Put cream, sugar and vanilla in a ziploc bag in the jar.
Step 2: Shake it like a polaroid picture!
Step 3: Remove bag from the jar.
Step 4: Enjoy delicious ice cream!
Now we just need to collect a bunch of jars so we can share frozen dessert with the citizens of Black Rock City.
If we have enough time, I'd also like to decorate the jars so they are more likely to become useful containers and not moop.