Stir together oyster sauce, garlic, rice wine, sugar, soy seasoning sauce, dark soy sauce, and crushed Kampot peppercorns in a small bowl.
Stir together cornstarch and 2 tablespoons water in a medium bowl until cornstarch is dissolved; add beef, and toss to coat. Add 1/4 cup of the oyster sauce mixture; cover and refrigerate 8 hours or overnight. Cover remaining oyster sauce mixture, and set aside.
Heat olive oil in an induction wok set on high. Carefully add beef mixture to wok, and cook, shaking wok often, until beef has a brown sear, 4 to 5 minutes. Add red onion and remaining oyster sauce mixture, and cook, shaking wok often, 2 more minutes.
Stir together lime juice, sea salt, and coarsely ground Kampot peppercorns. Place beef, lettuce leaves, and tomatoes on a platter, and serve with lime sauce.