In a small mixing bowl, whisk together the brown sugar, paprika, salt, onion powder, cayenne pepper, dried thyme, dried oregano, and ground black pepper.
Add the cubed steak to a large Ziploc bag. Pour in all of the spice mixture and massage through the steak thoroughly. Seal the bag and refrigerate for a minimum of 1 hour. (No longer than 3 hours.)
Add the vegetable oil to a large skillet and over medium heat, sear the steak cubes on all sides for 2-3 minutes. (Do this in batches so that you don't over crowd the skillet. Adding too much of the steak at one time will result in more steam and you won't get a good sear on the steak without cooking it for too long.)
Once the steak has all been seared, place it on a plate and set aside. Add the butter and the garlic to the skillet. Cook until the garlic is fragrant and lightly browned - about 3 minutes.
Add the steak back to the skillet and stir into the butter and garlic mixture. Turn off the heat and continue to toss the beef in the butter for 2-3 minutes.