Flank Steak with Tomato-Balsamic Sauce

This sauce also goes well with sauteed chicken breasts or pork chops.
Preheat a large skillet over medium-high heat. Add the olive oil; stir to coat. Sprinkle the steak with salt and 1/4 teaspoon pepper. Place the steak in the skillet and cook for 5 minutes on each side or until desired browning. Transfer the steak to a cutting board; let stand for 5 minutes. Cut across the fibers in thin slices.Add the garlic and shallots to the skillet; saute for 1 1/2 minutes or until lightly browned. Add the vinegar and cook for 1 1/2 minutes or until the liquid has almost evaporated. Add the tomatoes, 1/4 cup basil, 1/4 cup spring onions, and the remaining 1/4 teaspoon pepper. Cook for 2 minutes or until the tomatoes are tender and start to release liquid, stirring occasionally. Serve the tomato mixture on top of the sliced steak. Sprinkle with the remaining basil and remaining green onions.