Season the steak bites with salt, pepper, and red pepper flakes, stirring to coat.
Heat a large skillet over medium-high heat and add avocado oil.
Add the steak bites in a single layer and cook for 3-4 minutes, stirring occasionally, until browned. (Cook in batches if needed.)
Remove the steak from the skillet and set aside.
Remove excess water from the skillet, then add butter or ghee.
Add garlic and sauté for 1 minute.
Return the steak to the pan and cook for 1-2 minutes, stirring to coat in the butter sauce.
Remove from heat, stir in parsley, garnish with green onion, and serve.