Ingredients

  • 1 tablespoon vegetable oil
  • 1 to 1 1/2 pounds flank steak, sliced into 1 1/2-inch wide strips
  • Kosher salt and freshly ground black pepper
  • 1 large red onion, quartered and thinly sliced
  • 1 large tomato, coarsely chopped
  • 1 garlic clove, finely minced
  • 1 teaspoon soy sauce
  • 1 tablespoon red wine vinegar

Method

  • Heat the oil in a large wok or skillet over medium-high heat.
  • Add the steak, season with salt and pepper, and stir-fry until the meat is browned on all sides, about 8 to 10 minutes.
  • Using tongs, transfer the steak to a plate and set aside.
  • To the drippings in the pan, add the onion, tomato, and garlic; season with salt, and pepper.
  • Cook and stir it until the onions are soft and the tomatoes start to break down, about 2 to 4 minutes.
  • Return the beef to the pan, add the soy sauce and red wine vinegar.
  • Cook for 1 minute, season with salt and pepper, to taste, and serve.