Place steak cubes in a mixing bowl; season with salt, pepper, paprika, garlic powder, and Italian Seasoning. Toss to combine.
Heat 1 tablespoon vegetable oil in a large cast iron skillet or a heavy-bottomed skillet over medium-high heat.
Add steak bites to the hot skillet in a single layer. If it doesn't sizzle, the skillet is not hot enough.
Sear the steak bites for 1 minute - do not move them around.
Using tongs or a spatula, flip the steak bites over.
Add 2 tablespoons butter and stir in half of the minced garlic.
Continue to cook for 1 to 2 more minutes, or until done. DO NOT OVERCOOK.
Transfer steak bites to a plate and keep covered.
Add remaining vegetable oil to the skillet and heat over medium-high heat.
Stir in the sliced mushrooms and season with salt and pepper.
Cook for 3 minutes, or until browned.
Add remaining butter and stir in the rest of the garlic; let cook 2 to 3 more minutes, or until soft.
Stir the steak and drippings back into the skillet and cook for 30 more seconds or until heated through.
Remove from heat.
Let stand 5 minutes.
Garnish with parsley and serve.