01 - Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large skillet over medium-high heat. Season beef pieces with salt and pepper, then arrange in a single layer. Sear for 2 to 3 minutes per side until deeply browned. Work in batches if necessary, then transfer browned beef to a plate and set aside.
02 - Reduce heat to medium and add the remaining olive oil and butter to the skillet. Add the diced onion and mushrooms, if using, and sauté for 2 to 3 minutes until softened. Stir in the minced garlic and cook for 1 additional minute until fragrant.
03 - Sprinkle the flour over the sautéed vegetables, stirring continuously for about 1 minute to cook off the raw flour taste and form a light roux.
04 - Slowly pour in the beef broth while stirring and scraping up any browned bits from the bottom of the pan. Stir in the Worcestershire sauce and dried thyme. Bring to a gentle simmer.
05 - Return the seared beef and any accumulated juices to the skillet. Cook uncovered, stirring occasionally, for 8 to 10 minutes until the beef is tender and the gravy has thickened to your preferred consistency.
06 - Taste the gravy and adjust seasoning with salt and pepper as needed. Sprinkle with fresh parsley and serve hot over rice, mashed potatoes, or egg noodles.