Steam the cauliflower florets until they are very tender, about 10-12 minutes.
While the cauliflower steams, trim the ends of the green beans.
Heat the olive oil in a skillet over medium heat and add the green beans, sautéing for 5 minutes until crisp-tender.
Add the minced garlic to the green beans and cook for another 1-2 minutes until the garlic is golden and fragrant, then set aside.
Pat the sirloin steak dry with paper towels and season both sides with salt and black pepper.
Heat half of the ghee in a heavy cast-iron skillet over medium-high heat until shimmering.
Sear the steak for 4-5 minutes per side for medium-rare, then remove from the pan to rest for 5 minutes.
Drain the steamed cauliflower and place it in a blender or food processor with the remaining ghee and a pinch of salt.
Pulse until the cauliflower reaches a smooth, creamy mash consistency.
Slice the steak against the grain and serve alongside the mashed cauliflower and garlic green beans.