Heat olive oil in a large skillet over medium-high heat.
Season the sirloin tips with salt and pepper, then add to the skillet.
Sear the meat on all sides until browned, about 5-7 minutes.
Remove the meat from the skillet and set aside.
In the same skillet, add diced onions and cook until translucent, about 3-4 minutes.
Stir in minced garlic and cook for an additional minute until fragrant.
Pour in the beef broth and Worcestershire sauce, stirring to combine.
Return the seared sirloin tips to the skillet, bringing everything to a simmer.
Mix cornstarch with a small amount of water to make a slurry, then add it to the skillet.
Reduce heat and cook for an additional 15-20 minutes, stirring occasionally.
