01 - Pat steak cubes dry with paper towels. Toss with 1 tablespoon olive oil, kosher salt, and freshly ground black pepper. Set aside.
02 - Heat a large skillet over medium-high heat. Add 1 tablespoon olive oil and mushrooms. Season with salt and cook for 4 to 5 minutes, stirring occasionally, until mushrooms are golden and tender. Transfer to a plate.
03 - In the same skillet, add half of the steak cubes in a single layer. Sear undisturbed for 2 minutes, then flip and cook for 1 to 2 minutes until browned and medium-rare. Remove to a plate and repeat with remaining steak cubes.
04 - Reduce heat to medium. Add butter to the skillet and melt. Stir in minced garlic and thyme, cooking for 30 seconds until fragrant.
05 - Return steak bites and mushrooms to the skillet. Toss to coat evenly in the garlic butter for 1 minute. Drizzle with lemon juice and sprinkle with chopped parsley.
06 - Serve immediately, garnished with additional parsley if desired.