Creating Beef Stir Fry with Vegetables is straightforward if you follow these simple steps:

1. Prepare the Beef: Thinly slice the beef sirloin against the grain. This ensures tenderness.
2. Marinate the Beef: In a bowl, mix the beef with soy sauce, oyster sauce, and cornstarch. Let it marinate for 10 minutes.
3. Heat the Pan: In a large skillet or wok, heat the vegetable oil over medium-high heat.
4. Cook the Beef: Add the marinated beef to the skillet. Stir-fry for 3-4 minutes until browned. Remove from the pan and set aside.
5. Add Garlic and Ginger: In the same pan, add the minced garlic and ginger. Stir-fry for about 30 seconds until fragrant.
6. Add Vegetables: Add the mixed vegetables to the pan. Stir-fry for 5-7 minutes until they are tender yet crisp.
7. Combine: Return the cooked beef to the pan. Toss everything together and stir-fry for an additional 2-3 minutes.
8. Season: Taste and season with salt and pepper as needed.
9. Serve: Remove from heat and serve over cooked rice or noodles.

These clear steps will guide you in creating this incredible dish effortlessly.