Tender beef slices are wok-tossed with ripe tomatoes in a tangy, lightly sweet sauce. This fresh, healthy dish is high in protein and naturally lower in calories for those on a calorie deficit.
In a medium bowl, toss sliced beef with soy sauce, oyster sauce, cornstarch, and black pepper. Let marinate for at least 10 minutes for deeper flavor.
Cut tomatoes into large wedges and slice onion thinly; mince the garlic and slice scallions into 2-inch batons for uniform texture.
Heat a wok over high heat, then add vegetable oil and quickly stir-fry the beef for 1–2 minutes just until browned but not fully cooked; remove beef and set aside.
In the same wok over medium-high heat, add garlic and onion; sauté for 30–45 seconds until fragrant, then add tomatoes and sugar. Stir-fry just until tomatoes start to soften and release juices.
Return beef to the wok with vegetables, stir in scallions and sesame oil, and quickly toss everything for 1–2 minutes on high heat until beef is just cooked through and sauce coats evenly. Serve hot.