Beef with Tomatoes

1 pound beef steak, round or flank
2 tablespoons dark soy sauce
½ teaspoon salt
teaspoon pepper or to taste
2 teaspoons cornstarch
½ teaspoon baking soda
4 large tomatoes
3–4 tablespoons oil for stir-frying
3 slices ginger, minced
½ cup beef broth
1 tablespoon oyster sauce
1 teaspoon sugar
1 tablespoon cornstarch
4 tablespoons water
¼ teaspoon sesame oil

1. Cut the beef across the grain into slices that are approximately 1½ –2 inches
   long. Add the dark soy sauce, salt, pepper, cornstarch, and baking soda to
   the beef. Marinate the beef for 20 minutes.
2. Bring a large pot of water to a boil. Blanch the tomatoes. Peel off the skin
   and cut each into 6 equal pieces. (Be sure to remove the tomatoes from the
   boiling water before they soften.)
3. Add 2 tablespoons oil to a preheated wok or skillet. Add the beef. Fry until
   it changes color and it is nearly cooked through, turning it over once. Fry in
   batches if necessary. Remove the beef from the wok.
4. Wipe the wok if necessary and add 1–2 tablespoons oil. When the oil is hot,
   add the ginger and stir-fry briefly until aromatic. Add the tomatoes and stirfry briefly, making sure they don’t soften too much.
5. Add the beef broth, oyster sauce, and sugar, and bring to a boil. Add the
   cornstarch mixed with water to the middle of the wok, stirring to thicken.
   Add the beef back into the wok. Cover and simmer until everything is
   cooked through. Drizzle with the sesame oil.