Step 1: Prepare the Beef

1. Slice the Beef: Slice the beef thinly against the grain for maximum tenderness. Place the beef in a medium bowl.
2. Marinate: Add 2 tablespoons of soy sauce and the cornstarch to the beef. Toss to coat evenly and set aside to marinate while you prepare the vegetables and sauce.

Step 2: Make the Sauce

1. Combine Ingredients: In a small bowl, whisk together the soy sauce, oyster sauce, hoisin sauce, rice vinegar, honey, and crushed red pepper flakes (if using). Add the water or beef broth and stir until well combined. Set aside.

Step 3: Stir-Fry the Vegetables

1. Heat the Oil: Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat.
2. Cook the Vegetables: Add the bell peppers and onions. Stir-fry for 3-4 minutes, or until the vegetables are slightly tender but still crisp. Add the garlic and ginger, and stir for another 30 seconds. Remove the vegetables from the skillet and set aside.

Step 4: Cook the Beef

1. Sear the Beef: In the same skillet, add a bit more oil if needed. Add the marinated beef in a single layer and cook for 2-3 minutes per side, or until browned and cooked through. Cook in batches if necessary to avoid overcrowding the pan.
2. Return Vegetables: Once all the beef is cooked, return the vegetables to the skillet.

Step 5: Add the Sauce and Combine

1. Pour in the Sauce: Pour the prepared sauce over the beef and vegetables. Stir to combine, and cook for 2-3 minutes, or until the sauce thickens slightly and coats the ingredients evenly.

Step 6: Assemble the Rice Bowls

1. Prepare the Base: Divide the cooked rice among four bowls.
2. Add the Beef and Vegetables: Spoon the beef and pepper mixture over the rice.
3. Garnish and Serve: Top with chopped green onions, sesame seeds, or a drizzle of sriracha if desired. Serve immediately.