01 - Pat steak cubes dry with paper towels. Toss in a bowl with 1 tbsp olive oil, 1 tsp salt, and 1/2 tsp pepper until evenly coated. Set aside at room temperature while preparing other ingredients.
02 - Heat 1 tbsp olive oil in a large skillet over medium-high heat. Add quartered mushrooms, season with 1/4 tsp salt and 1/4 tsp pepper. Sauté for 4-5 minutes, stirring occasionally, until golden brown and tender. Transfer to a plate and reserve.
03 - Increase heat to high. Add steak cubes in a single layer, working in batches if necessary to avoid overcrowding. Sear for 2-3 minutes, turning frequently to brown all sides. Cook until desired doneness is reached.
04 - Reduce heat to medium. Push steak to one side of the skillet. Add butter and minced garlic to the empty space. Sauté garlic for 30 seconds until fragrant, then stir into the steak to combine.
05 - Return sautéed mushrooms to the pan. Add fresh parsley, thyme leaves, and red pepper flakes. Toss everything together for 1-2 minutes until evenly coated in the garlic butter sauce and heated through. Remove from heat immediately.
06 - Transfer to a serving platter or individual plates. Garnish with additional fresh parsley if desired. Serve immediately while hot.