In a large skillet with a lid, melt the butter over medium heat.
Add the ground lamb and break it apart with a wooden spoon as it browns.
Dice the onion and add it to the pan. Continue cooking and breaking up the meat until the onion softens and the lamb is mostly browned (about 6–8 minutes).
Stir in the diced tomatoes (with juices), curry powder, turmeric, cinnamon, cayenne, ginger, sea salt, black pepper, and garlic powder. Mix well.
Reduce heat to medium-low, cover, and simmer 10–12 minutes, stirring occasionally, until the flavors meld and the sauce thickens slightly.
While the keema simmers, heat the cauliflower rice according to package instructions (microwave or stove-top—about 4–5 minutes).
When the meat is fully cooked, stir in the green bean pieces. Cover and cook another 5–7 minutes until the beans are tender-crisp.
In bowls or plates, spoon a generous base of warm cauliflower rice, then top with a big scoop of the lamb keema.
Garnish with extra fresh parsley or cilantro if you like, and dig in!