Marinate the meat with a mix of cornstarch, oil, and salt. Set aside.
In a small bowl, combine the ketchup, soy sauce, sugar, sesame oil and pepper. Set this sauce aside.
Spread the beef around in a pan and sear for 1 minute on high heat. Remove and set aside.
Heat another tbsp of oil in the pan over medium heat. Add ginger and let caramelize for 10 seconds. Turn the heat up to high, add garlic, shallot, and the white portions of the green onion. Toss to combine.
Add tomatoes to the pan. Spread them around the pan in an even layer and let sear for 15 seconds. Add the rice wine vinegar and stir-fry the mixture for another 10 seconds.
In the same pan, add the sauce base and stir until bubbling. Add the beef in the bowl to the pan. Stir–fry on high heat until mixed well.
Toss in the remainder of the green onions and add cornstarch. Let the sauce cook until cornstarch is cooked. Serve immediately.