Add the beef to a bowl and season with salt and pepper. Set aside while making the sauce.
In a small bowl, add the Worcestershire sauce, soy sauce, oyster sauce, sugar and crushed red pepper flakes. Whisk until the sugar is dissolved and everything is combined.
Add oil to a large skillet over medium heat. Cook garlic until lightly golden and crispy. Remove from the skillet.
Increase the heat to medium-high and add the beef. Sear for 1-2 minutes per side. Add the sauce and butter, tossing the beef to coat it and allowing the butter to melt. Top with the garlic and serve.
Notes
Be consistent with the size you cut the beef so it cooks evenly.
You can let the beef marinate with the salt and pepper and 2 tablespoon of the sauce for an hour as it helps tenderize the beef even more.
Cook the beef in batches so you don't overload the skillet and cool it down. You want to cook the beef quickly and adding too much at a time will slow the cooking process.
Do not overcook the beef or it will be tough. Max 2 minutes per side.
If you want more heat, add crushed red peppers in ¼ teaspoon increments.