Place vinegar in a medium bowl. Slowly whisk in the oil until emulsified. Season with salt and pepper, to taste.
Preheat the broiler.
Broil skirt steak until cooked to desired temperature, about 5 minutes. While broiling, baste it occasionally with soy sauce. Remove from heat and let stand while you prepare the salad.
Place lettuce in a large bowl. Drizzle with some of the vinaigrette, sprinkle with oregano, and season with salt and pepper, to taste; toss to combine. Add more dressing, if desired. Divide salad among 2 plates. Arrange tomato, onion, olives, and pepperoncini around the plate.
Slice steak into thin pieces and divide evenly among salads. Serve.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.