Put a bootloader on.
Put your Uno back together.
Download & install westfw's optiloader.
Connect up power/gnd, D13 to D13, D12 to D12, D11 to D11, Uno D10 to mini's Reset.
Reset the Uno, it will detect the mini & put the bootloader on it.
See the video in this thread
http://arduino.cc/forum/index.php/topic,68183.0.html