Step 1

Set out steak at least 30 minutes before cooking. Cut into bite-sized pieces.

Step 2

Heat 2 tablespoons of butter and 1 tablespoon of oil in a large cast iron or non-stick skillet. Over medium-high heat, sear the steak pieces, adding a single layer of meat to the pan at a time, and allowing ample room around the steak. Work in batches to quickly brown on all sides, and then remove the seared steak pieces.

Step 3

Deglaze the pan with a splash of vinegar, red wine, beef stock, or even water. Heat over low and scrape the browned bits from the skillet. Add scrapings to the crockpot.

Step 4

In the crock of a slow cooker, layer the sliced onions and then the seared steak over the top.

Step 5

Whisk together the garlic, beef broth, salt, pepper, Worcestershire, and cornstarch and pour over the steak.

Step 6

Cut the remaining butter into pieces and spread out over the top of the meat.

Step 7

Cover and cook on HIGH for 3-4 hours or on LOW for 6-8 hours.