I want a car that can fly. :P
I say you have two options:
A quality dutch oven . This can do it all, although steaming might be difficult unless you can find a steamer insert for your dutch oven. It's certainly the closest you're gonna get to a slow cooker.
A quality stock pot with a steamer insert (or two). I have a great 12 qt stock pot withgreat 12 qt stock pot with 2 steamer inserts. I deep fry in it often, the high sides contain spatter. The only thing it doesn't do well is slow cook.