There is a new “bare-metal” UEFI sample, a standalone C program with no use of external (eg, Tianocore) headers. It is also an example of showing how to write and run a UEFI inside OVMF.
https://github.com/cupnes/bare_metal_uefi
https://github.com/utshina/uefi-simple
http://d.hatena.ne.jp/shina_ecc/20140819/1408434995
http://wiki.osdev.org/UEFI_Bare_Bones
http://wiki.osdev.org/Bare_Bones