[squarefoot]

The only way to anonymize it enough, also defeating any attempt at cookie/malware injection to me would be to create a VM with the strict necessary to run Tor browser and clone it for single use, that is, a script that clones the VM, opens it, let you use Tor browser, then as you close the browser the VM is also closed and deleted. The script could also create the next VM changing bits here and there for added anonymization (OS and browser signature, screen and window size, mouse settings, etc) while the old one is still running, to save time.

[sseagull]

This is largely the motivation for TAILS: https://en.wikipedia.org/wiki/Tails_(operating_system)

And also Whonix: https://en.wikipedia.org/wiki/Whonix

Using the DVD image in a VM would largely suffice for most users. For even more security, you would use the live image on a throwaway laptop at a coffee shop or something, but that's not exactly practical for everyday use.

[rbanffy]

I remember I used immutable VMs for a lot of testing - those reset to the last saved state when shut down and made a lot of tests more easily repeatable. This is a sensible thing to do for privacy as well - any cookies you gain during your session you shed on reboot.