In a large skillet or Dutch oven, heat olive oil over medium-high heat. Add beef in batches, searing until browned on all sides. Remove to a plate.
In the same skillet, reduce heat to medium. Add diced onion and cook until softened, about 3–4 minutes. Stir in garlic and cook for another 30 seconds.
Return beef to the skillet. Add beef broth, Worcestershire sauce, soy sauce (if using), onion powder, thyme, black pepper, and a pinch of salt. Stir, scraping up any browned bits from the bottom. Bring to a boil, then reduce heat to low and cover. Simmer for 45–55 minutes, or until beef is tender.
In a small bowl, mix cornstarch and cold water until smooth. Slowly pour into the simmering beef, stirring constantly. Cook for another 3–5 minutes, until the gravy thickens to your desired consistency.
Serve beef tips and gravy over mashed potatoes, egg noodles, or rice. Garnish with parsley if desired.