This is one of my all time favorite Taiwanese dish. My best guess why this is called "fly's head" is the resemblance to remaining buds on the tips of garlic chives as it is the main ingredient. A great version I had was from the Main Street Imperial Gourmet in Flushing, NY (great option if you are stuck in La Guardia airport)
It's made with diced garlic chive and tips, minced pork, thai chilli, and fermented black beans all mixed together. Its subtle chive and pork flavors dominate, but the accents of chilli and black bean takes this dish to a whole another level and makes it addictive. It's one of those dishes you order again and again everytime you go, even during the beginnings of discovering a restaurant.
Any experience with this dish locally?