oh wow...lucky you! I'm sorry. My dog got a small nick on his ear and it broke open and spattered my walls with blood for weeks and weeks....it was a pain in my patootie to get it to heal.
Does your dog have prick ears or long? How big is the cut? Is it a nick or is it clean through the ear leather? I'm asking because if it's large, it may need stitches.
If he has long ears, this is what I did with my dog. I put antibiotic ointment on the ear, wrapped it with gauze, then put the injured ear on top of his head. Then I wrapped his entire head with vetwrap to keep the ear immobilized. You have to be VERY careful to not get the vetwrap too tight, as it will interfere with breathing. I also had to get a sticky ace bandage type tape from my vet called Elastikon to secure the top and bottom of the vetwrap to keep it from shifting.
I changed this every day. Once it started to heal, it developed huge thick scabs that were very fragile, so I started putting Austin in the tub during bandage changes and directing a hard spray of water on the ear. The cold hydrotherapy helped close off the tiny capillaries and kept the scabs under control.