Grate the cauliflower through the large holes of a box grater.
Combine the shredded cauliflower with the egg, minced onion, 1/4 teaspoon salt, 1/8 teaspoon pepper and garlic powder; stir to combine.
Heat 1 teaspoon coconut oil in a medium nonstick skillet over medium-high heat.
Add half the cauliflower mixture to the pan and gently press down with a spatula to flatten, working to keep the hash brown together as much as possible.
Cook 3 to 5 minutes, until the edges start to turn golden brown, then cook for 1 minute more.
Carefully flip the hash brown and cook for an additional 3 to 4 minutes to let the edges brown and the cauliflower and onion cook through. Remove to a plate and repeat with the remaining oil and cauliflower mixture, wiping out the pan if necessary.