How to restore system from network drive?
UPDATE: On recent versions of macOS (tested with High Sierra 10.13.4) you can restore from a networked drive directly from the "Restore from Time Machine Backup" option in the recovery mode. The following steps are not required (but are super awesome!).



Prerequisites:  

– admin account &amp; password
– AFP/SMB-share &amp; server IP-address


Boot the Computer to Recovery Mode.
Open Terminal in the Utilities menu
At the prompt enter: cd /Volumes
Create a sub-directory in Volumes as a mount point for your time machine share:
mkdir TimeMachine
Enter cd TimeMachine
Enter pwd. pwd should show /Volumes/TimeMachine
Mount the network share with your admin loginname &amp; password:

mount -t afp afp://adminname:password@ServerIPAddress/ShareName /Volumes/TimeMachine


If your password contains wonky characters like :@\/ use URL encoding to protect them
Enter: ls -la. Note the exact name of your sparsebundle.
Enter: hdid /Volumes/TimeMachine/NameOfYourSparseBundle.
You may enter the first letters of the sparsebundle name and then hit TAB.
Hitting tab should auto-complete the Time Machine sparsebundle name. It may not look the same as above as it escapes spaces and special characters.
After auto-completing the name, hit return. 
If you return to the prompt the sparsebundle has been opened.
Enter exit and ⏎ and quit Terminal.
Example steps 3-11:


Select Restore From Time Machine Backup and click Continue.


After a search it should show you the Time Machine Backups directory as a volume that contains your backup. Select that (in my example 'Time Machine Backups') and click Continue.


In the next screen you will see all the backups that you can restore from listed by time and date.


Select the backup you want to restore and continue and finally choose your destination disk: