Emeril's Flank Steak with Chimichurri Sauce

Father's Day is just around the corner. Celebrity chef, TV host and author Emeril Lagasse offers this great meal for idea for Dad's special day.

Ingredients :

• 1 1/2 cups dry sherry
• 1/2 cup sherry vinegar
• 1 cup thinly sliced red onion
• 2 tablespoons minced garlic
• 1/2 cup olive oil
• One 1 1/2- to 2-pound flank steak
• 2 teaspoons salt
• 1 teaspoon freshly cracked black pepper
• Chimichurri Sauce (recipe follow below), for serving

Chimichurri Sauce :

• 1 cup extra-virgin olive oil
• 2/3 cup sherry vinegar
• 2 tablespoons freshly squeezed lemon juice
• 1 cup chopped fresh flat-leaf parsley
• 1/4 cup chopped fresh basil
• 3 tablespoons minced garlic
• 2 tablespoons minced shallots