I'm a lazy guy and I was simply tired to use the stock recovery all the time the new OTA arrives, so I decided to make a prerooted ROM and share it with you. The modification is very simple and required me to edit just a few lines in the updater-script.
The coolest thing is that you can flash it using TWRP.
I haven't noticed any bugs so far, so tell me if the method works for you.
Cyanogen OS 12.1 Rooted, ROM for the Lenovo Zuk Z1
ROM OS Version: 5.1.x Lollipop
ROM Kernel: Linux 3.4.x
ROM Firmware Required: Latest Firmware
Based On: Cyanogen OS
Last Updated 2016-04-06