Marinate the beef 10–15 minutes with soy sauce, a pinch of pepper, and a splash of sesame oil. Not a spa day, but close enough for flavor therapy.
Whisk together hoisin sauce, oyster sauce (if using), beef broth, and cornstarch slurry. This is your glossy, restaurant-grade base—no roux required.
Heat a large skillet over high heat and add 1 tablespoon oil. Sear the beef in batches until browned; don’t crowd the pan. Remove and set aside.
In the same pan, add the remaining oil. Sauté garlic, onions, and peppers just until they start to blister and soften—about 3–4 minutes.
Pour in the sauce mixture, then return the beef to the pan. Toss to coat and cook 1–2 minutes until everything glazes with that shiny sauce.
Taste and adjust salt or pepper. If the sauce is too thick, splash in a little more broth. If it’s too thin, simmer a moment longer. You’re aiming for a glossy, clingy finish.