Slow Cooker Flank Steak

A slow cooker with sliced flank steak topped with carmelized onions.

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5 from 2 votes

Slow Cooker Flank Steak is an easy recipe for a delicious steak dinner with tender and juicy flank steak, every time.

Course Main Course

Cuisine American

Keyword crockpot flank steak, flank steak in the slow cooker, slow cooker flank steak

Prep Time 15

Cook Time 6

rest time 10

Total Time 6 25

Servings servings

Calories 240kcal

Author Eileen Murphy Kelly

Equipment

Ingredients

2 pound flank steak Note 1
1 teaspoon chili powder
1 teaspoon garlic powder
½ teaspoon granulated sugar
½ teaspoon salt
½ teaspoon black pepper
1 Tablespoon olive oil
1 cup yellow onion (peeled and sliced thin) Note 2
2 Tablespoons red wine vinegar
½ teaspoon Dijon mustard

Instructions

Season the 2 pound flank steak with 1 teaspoon chili powder, 1 teaspoon garlic powder, ½ teaspoon granulated sugar, ½ teaspoon salt, and ½ teaspoon black pepper
Heat a heavy skillet or cast-iron pan over medium-high heat. Add 1 Tablespoon olive oil and swirl around the skillet. Add the seasoned flank steak to the skillet and cook until browned, about 3 minutes per side.
While the steak is browning, spread 1 cup yellow onion (peeled and sliced thin) in the bottom of the slow cooker.
When the steak is browned on both sides, transfer the steak to the slow cooker and place it on top of the sliced onions.
Pour 2 Tablespoons red wine vinegar into the skillet, scraping to pull up any brown bits. Whisk in ½ teaspoon Dijon mustardinto the skillet to blend with red wine vinegar. Pour the sauce over the steak.
Place the lid on the slow cooker. Cook on low for 4 hours. The meat will be tender and cooked through.
Transfer the steak to a cutting board. Let the steak rest for 10 minutes. Thinly slice the steak, against the grain. Serve with the onions and juices from the pan.
Serve with your favorite sides like mashed potatoes, green beans, or potato salad.

Notes

Tips and FAQs above with important tips and questions that can help make a delicious recipe.

Note 1: This recipe works well with a London broil.

Note 2: 1 cup of onion is about 1 medium-sized yellow onion.

I'm not a registered dietician, I do my best to provide the most accurate nutritional values. Any nutritional data I provide is an approximation. Actual dietary information can vary based on ingredients and portion sizes.

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