Preparation

Thinly slice the beef on the diagonal into 1/4"-thick slices. Cut large pieces in half. Sprinkle with 1/4 teaspoon of the salt and the black pepper. Set aside. In a large saucepan, stir together the beef broth, wine (if using), tomato sauce, and thyme. Cover and bring to a boil over high heat. Reduce the heat to low and simmer, covered, for 10 minutes. Meanwhile, in a large nonstick skillet, warm the oil over medium-high heat until hot but not smoking. Add half the beef slices and cook, turning once, for 2 minutes, or until browned. Transfer to a clean bowl. Cook the remaining beef. Add the onion, bell peppers, garlic, and the remaining 1/4 teaspoon salt to the skillet. Toss to mix well and add 2 tablespoons of the water. Lower the heat to medium and cook, stirring often, for 10 minutes, or until the vegetables are tender. If the pan gets dry, add the remaining 1 tablespoon water. Add the tomatoes and cook, stirring often, for 5 minutes, or until softened. Add the beef and any juices and the vegetables to the broth mixture. Warm through but don't boil.