Ingredients:
1 small red onion, quartered
1/3 cup balsamic vinegar
2 tablespoons chopped fresh oregano
2 teaspoons minced garlic
1 1/2 pounds flank steak
1/4 teaspoon salt
1/4 teaspoon black pepper

Directions:
1. Slice one-quart of the onion and dice the rest of the onion. Mix onion with vinegar, oregano, and garlic. Combine 1/4 of mixture with the sliced onion and set aside.

2. Sprinkle both sides of steak with salt and pepper and prick well with a fork. In a large zip up bag combine steak with the 1/4 of marinade and marinate for an hour or overnight.

3. Heat broiler and cook steak with remaining marinade and onions for 4-5 minutes per side. Let cool and serve!