Chinese Beef and Onion Stir Fry

Enjoy this quick and flavorful stir-fry featuring tender beef, crisp onions, and a savory sauce, perfect over rice or noodles.

For the Stir Fry:
- 1 lb beef sirloin or flank steak, thinly sliced against the grain
- 2 tablespoons vegetable oil
- 1 large onion, sliced
- 3 cloves garlic, minced
- 1-inch piece ginger, grated
- 1 bell pepper, sliced (optional)
For the Sauce:
- 2 tablespoons soy sauce
- 1 tablespoon hoisin sauce
- 1 tablespoon oyster sauce
- 1 tablespoon rice vinegar
- 1 tablespoon cornstarch mixed with 2 tablespoons water (for thickening)
- 1/4 cup water or beef broth
For Garnish:
- 2 green onions, chopped
- Sesame seeds (optional)
Serving:
- Cooked rice or noodles