1In a small bowl, mix the soy sauce, oyster sauce, and cornstarch until smooth. Set aside.
Heat the olive oil in a large skillet over medium-high heat.
Add the minced garlic and stir-fry for about 30 seconds until fragrant.
Add the sliced beef sirloin to the skillet and stir-fry for 3-4 minutes until browned.
Add the broccoli florets to the skillet and stir-fry for another 3 minutes until they are bright green and tender-crisp.
Pour the sauce mixture over the beef and broccoli, stirring well to coat everything evenly.
Cook for an additional 2 minutes until the sauce thickens.
Remove from heat and serve hot.