Mom's Butter Top Loin

 Steak was fatty. I left it in its entire large size (8in long, 4-6 wide?) 

I tried to warm the meat to room-temperature. I pounded it with my fists briefly and rubbed in salt and pepper on both sides. I melted a enough avocado oil and butter to about half a centimeter high in a sauce pan, put in some minced garlic, and half a sliced onion. Then I put the steak in, covered it with a glass lid , and heated it from medium high (until boiling) to low on the stove. I left it about 5 minutes, then I flipped the steak. I tried to look at the middle until it looked decently cooked. It was slightly overcooked. 

Would take it off slightly undercooked for medium rare next time.