Using recovery key on erased FileVault encrypted SSD My understanding is that with FileVault enabled one can restart a Mac into its Recovery System and erase the hard drive/SSD using Disk Utility.
This procedure supposedly deletes the FileVault key, which means any data on the drive is useless as it can no longer be decrypted.

If a system is in the state described above but previously had a institutional (or personal) recovery key enabled does it mean that key could still be used to recover the data?

My intention is to be able to securely dispose of the FileVault key as well as other recovery keys that might have been set but I was not able to find official documentation from Apple confirming a secure procedure.
Your data is unrecoverable in the hands of an average data recovery attempt. First step Data Recovery. Low class data recovery doesn’t recovery everything and can scramble some files making decrypting the files very difficult. Nearly impossible without the recovery key. If the recovery key is known it’s, possible. This is very time and resource consuming and very difficult to target specific data. However If an organization wants to spend an astronomical amount of money to extract and decrypt data they pretty much can unless you destroy the disk. Zeroing out a drive makes it harder for the data to be recovered but takes a very long time and puts a lot of ware and tear on the disk.