Grilled Flank Steak with Red Onions - Slender Kitchen

Grilled Flank Steak with Red Onions

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(4 Old SmartPoints™) (5 PointsPlus®)

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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.

I am always shocked to hear that many people trying to eat healthy 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 difficultly is that it can be tough if it isn't cooked correctly. They 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. 

Here are some notes for cooking this 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.

Looking for more healthy steak recipes?

Prep Time

Grilled Flank Steak with Red Onions

Prep Time: 
Cook Time: 
Total Time: 


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

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


Meet Martha Mckinnon

Martha is a lifetime WW committed to balancing her love of food and desire to stay slim while savoring life. Her blog,, is a popular resource for easy healthy recipes, success stories and weight loss tips to help you eat great and lose weight. A huge fan of the slow cooker and confessed cookbook addict, when she's not experimenting in the kitchen, you'll find her helping beginners over the age of 50 discover the powerful benefits of yoga.  Learn More
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Grilled Flank Steak with Red Onions made with a simple, homemade marinade and delicious, grilled onions for an easy, healthy dinner.
† SmartPoints™ and PointsPlus® calculated by Slender Kitchen; Not endorsed by Weight Watchers International, Inc.
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