Prepare the Steak: Season the beef steak generously with salt, black pepper, minced garlic, thyme, and rosemary. Rub the seasonings into the meat and let it marinate for at least 30 minutes at room temperature.

Sear the Steak: In a large skillet, heat the olive oil over medium-high heat. Once hot, add the marinated steak and sear for 4-5 minutes on each side until a nice crust forms. Remove the steak from the skillet and set aside.

Cook the Onions: In the same skillet, add the sliced onions. Cook over medium heat, stirring occasionally, until the onions are caramelized and golden brown, about 10-15 minutes.

Add the Broth: Pour the beef broth and Worcestershire sauce into the skillet with the onions. Stir to combine, ensuring to scrape any browned bits from the bottom of the skillet for added flavor.

Return the Steak: Place the seared steak back into the skillet with the onion gravy. Reduce the heat to low, cover, and let it simmer for about 1 hour, or until the steak is tender and cooked to your desired doneness.

Thicken the Gravy (Optional): If you prefer a thicker gravy, mix the cornstarch with a tablespoon of cold water to create a slurry. Stir this into the gravy and cook for an additional 5 minutes until thickened.

Serve: Remove the skillet from heat. Slice the steak against the grain and serve it topped with the slow-cooked onion gravy. Garnish with fresh parsley.