01 -
Get a large bowl and toss the steak pieces in it. Add kosher salt and black pepper, mixing to coat everything evenly.
02 -
Warm up a skillet on medium-high heat. Pour in some vegetable oil and wait till it's really hot. Brown the steak bites in batches, adding oil if needed. Don't fully cook them yet.
03 -
Dump the browned steak bites into a 6-quart slow cooker. Add the thin onion slices and the garlic slices, giving it a gentle mix.
04 -
Drizzle the beef stock over the ingredients in the slow cooker. Sprinkle the au jus gravy mix evenly, then place the butter slices on top.
05 -
Place the slow cooker lid on. Let it cook 3-4 hours on high or 6-8 hours on low. Stir every hour, if you can.
06 -
Serve the warm steak bites alongside mashed potatoes, rice, or noodles if you'd like.