Mix all ingredients together in a ziploc or a large dish.
1/2 Cup Soy Sauce, 1/3 Cup Vegetable Oil, 2 Tablespoons Dark Brown Sugar, 1/4 Cup Worcestershire Sauce, 1 teaspoon Dijon Mustard, 4 Cloves Garlic, 2 Tablespoons Chives, 1 1/2 teaspoons Ground Black Pepper, 2 teaspoons Balsamic Vinegar
Add the flank steak and marinate (covered) in the fridge overnight or at least all day.
2 Pounds Flank Steak
Heat the gas grill to high heat. Remove the steak from the marinade and lay on the grill for 2 minutes per side. Then turn down to medium and cook another 7-10 minutes, flipping halfway again, or until an internal temperature of 130 degrees F (using a meat thermometer) for medium rare, or longer for medium etc. Remove and set aside to rest on a cutting board with foil draped over the top.
Meanwhile, place 1/2 of the remaining marinade in a sauce pan over medium heat.
Bring the marinade to a simmer for 10 minutes, set aside.
Slice the steak against the grain and serve with a drizzle of additional sauce if desired.
Notes
Flank steak is a lower quality of meat so cooking to well done will make it more chewy. It's incredibly flavorful and delicious when cooked properly!!Store left overs for 3-4 days in the refrigerator.