Heat a large skillet over medium-high. Add oil. Once hot, sear steak bites in batches until browned on all sides. You're just adding color—not cooking through.
Transfer seared steak to slow cooker.
In a bowl, whisk together bourbon, honey, ketchup, soy sauce, Worcestershire, vinegar, brown sugar, garlic, salt, and pepper. Pour over steak.
Cover and cook on low for 4–6 hours, until steak is fork-tender. Stir halfway through if possible.
Optional: For a thicker sauce, whisk cornstarch and water, then stir into the slow cooker 30 minutes before the end.
Serve warm, topped with parsley if desired.
