For a tasty salad dressing without oil, we mixed salsa with some vinegar. You can use any prepared salsa: hot or mild, red or green, plain or fruity.
In a small bowl, combine chili powder, oregano, cumin, and 1/2 teaspoon salt. Rub spice mixture evenly over flank steak to coat.
In a large skillet, heat oil over medium heat. Add steak; cook until browned on one side, 5 to 8 minutes. Turn; cook until browned on other side, 5 to 8 minutes for medium-rare (reduce heat if browning too quickly). Remove steak from skillet; let rest at least 5 minutes before thinly slicing.
In a medium bowl, whisk together salsa and vinegar; season with salt and pepper. Add arugula; toss to coat with dressing. Divide among four plates; serve with steak, and crumble goat cheese over the top.
To make this dish even lighter, use the broiler pan with nonstick cooking spray, and cook the steak, turning once, about 9 minutes total for medium-rare.