Grilled Flank Steak with Red Onions

Grilled Flank Steak with Red Onions made with a simple, homemade marinade and delicious, grilled onions for an easy, healthy dinner.

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Grilled Flank Steak with Red Onions with a tasty red wine vinegar marinade comes out tender and juicy on the grill and is served with amazing grilled red onions. Serve it with some grilled broccoli or grilled zucchini.

I am always shocked to hear that many people trying to eat healthily or count calories are scared to eat steak. Personally, steak is one of my favorite things to eat and I couldn't imagine giving it up. Luckily as long as you choose a nice, lean cut of beef then you can enjoy steak on almost any diet. And flank steak is the perfect cut when it comes to choosing a lean, flavorful steak.

Flank steak is a naturally lean cut of beef and has an intense, beefy flavor that's delicious. The one difficulty is that it can be tough if it isn't cooked correctly. The key to making flank steak tender is adding some marinade to break down the muscle fibers and cutting the steak in thin slice against the grain. 

With that in mind, you'll want to marinate your flank steak for at least an hour so it has time to absorb the flavor and become more tender. And when it comes to marinade, I really believe that simple is best since you want to be able to taste the great flavor of the beef. This simple marinade incorporates red wine vinegar, olive oil, lemon, oregano, salt, and pepper. You can switch out the oregano for rosemary, basil, thyme, or any other herb you like. You can also switch out the vinegar for what you have at home or what your family likes best. 

How long can you marinate flank steak?

Generally speaking, you will always want to marinate steak for at least a couple of ours. However, you can marinate steak overnight and up to 24-48 hours depending on the marinade. One note, marinades with lots of citrus or vinegar can begin to break down the meat so it isn't recommended to marinate steak in those types of marinades for too long. A couple of hours should suffice.

How long does flank steak take to grill?

Flank steak is normally a fairly thin cut of beef and therefore cooks pretty quickly on the grill. For a medium rare steak, 4-6 minutes per side usually works great. With that said, grills can vary in strength, so it is more important to pay attention to the internal temperature. For rare steak, you want a temperature of 125 degrees. Medium rare is 135 degrees, medium is 145 degrees, and well done is 165 degrees.  Flank steak can get tough if it overcooks, so I recommend medium rare or medium.

Tips for Making Grilled Flank Steak with Red Onions

  • Looking for a vegetarian option: Instead of the flank steak you can use portobello mushrooms, eggplant, tempeh, or tofu. If you decide to use tofu, make sure to press it beforehand to remove any excess liquid.
  • Want to use something other than steak: This recipe works with boneless skinless chicken thighs or breasts, lean pork chops, pork tenderloin, or turkey cutlets.
  • Consider a different vinegar: Red wine vinegar works really well in this recipe but you can also try it with balsamic vinegar, sherry vinegar, or white wine vinegar.
  • Switch up the vegetables: There are so many delicious veggies out there and you can use almost anything in this recipe. Try using zucchini, summer squash, bell peppers, eggplant, whole green onions, or asparagus.

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The Recipe
Grilled flank steak with red onions and peppers on a cutting board.

Grilled Flank Steak with Red Onions

PREP TIME: 1 Hours
TOTAL TIME: 1 Hours, 20 Min
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  • 3 tbsp red wine vinegar
  • 1 tbsp olive oil
  • 2 tsp dried oregano
  • 1 clove garlic, minced
  • 1/4 tsp black pepper
  • 1.5 lbs lean flank steak, trimmed of excess fat
  • 1 tsp salt
  • 1 red onion, sliced into rounds

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  • Nutritional Information and Points
Nutritional Facts
Serving Size: 3 slices steak and 1/4 cup onion
Amount Per Serving
Calories 199
Calories from Fat 85
% Daily Value *
Total Fat 10g
Saturated Fat 3g
Monounsaturated Fat 3g
Polyunsaturated Fat 0g
Cholesterol 78mg
Sodium 459mg
Total Carbohydrate 2g
Dietary Fiber 1g
Sugars 1g
Protein 25g

* Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.

The Nutritional Values provided are estimates only and may vary based on the preparation method.

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