Here is a great recipe for those beautiful Costco flank steaks you have been looking at! We are going to marinate the steak, cook it by sous vide and then top it with a delicious chimichurri sauce.
Sous vide is one of the best methods for cooking a flank steak as it will always come out incredibly tender and perfectly cooked.
If you would like more flank steak recipe ideas then please see the following:
Marinate the Flank Steak For Four Hours
Let’s start by packing some flavor into the meat.
Put the steak into a one gallon Ziploc bag and coat with the following marinade:
Flank Steak Marinade
- 1/2 cup soy sauce
- 1/4 cup olive oil
- 3 tbls fresh diced parsley
- 1 tbls fresh minced garlic
- 1 tbls black pepper
Let the steak marinate in the refrigerator for at least four hours but longer is better (overnight is fine).
Cook the Flank Steak by Sous Vide
Remove the steak from the marinade and pat dry then place the steak into a Foodsaver bag and vacuum seal.
Use your sous vide immersion heater to heat a water bath to 130F.
Place the steak in the water bath and cook for three hours. Check on the steak every now and then to make sure it isn’t floating on top of the water. Use a chip clip to hold the bag in place if needed.
This temperature will cook the steak to a perfect medium rare. If you like you steak more well done then increase the temperature to 140F.
Sear and Slice the Flank Steak after Sous Vide
After the flank steak has cooked for three hours remove it from the bag and discard the liquids. The steak will look dull grey and not very nice when it comes out of the bag but a nice sear will fix that.
How you sear the steak isn’t that critical. You can use a Weber gas grill, a sous vide torch or a cast iron skillet on your stovetop. Get whatever you are using hot as heck and then sear the steak for 90 seconds per side.
After the flank steak has been seared take a careful look at the steak and identify which way the grain is patterned. You want to make absolutely sure that you slice the steak against the grain for maximum tenderness.
Prepare the Chimichurri Sauce
Chimichurri is a classic sauce to pair with flank steak. Here is a wonderful recipe for the sauce.
- 1/2 cup extra-virgin olive oil
- 1/2 cup red wine vinegar
- 1/2 cup finely chopped fresh cilantro
- 1/2 cup finely chopped fresh flat-leaf parsley
- 2 Tbsp. finely chopped fresh oregano
- 1 small shallot, finely chopped
- 1 small jalapeño, seeded and finely chopped
- 1 tbls fresh garlic finely chopped
- 1 tsp. kosher salt
Combine ingredients and whisk well with a fork to combine.
Spoon the sauce of the slices of sous vide flank steak and enjoy!
Costco Flank Steak Sous Vide
- Foodsaver vacuum sealer
- Sous Vide Immersion Heater
- 1.5 lbs Flank Steak from Costco
- Flank Steak Marinade
- 1/2 cup Soy sauce
- 1/4 cup Olive oil
- 3 tbsp Fresh diced parsley
- 1 tbsp Fresh minced garlic
- 1 tbls Black Pepper
- Chimichurri Sauce
- Prepare the marinade.
- Place the flank steak in a Ziploc bag and pour in the marinade. Massage well to coat.
- Marinate the steak for four hours or up to overnight.
- Pat the steak dry and vacuum seal in a Foodsaver bag.
- Use an immersion heater to set a water bath to 130F.
- Place the steak into the water bath and cook for three hours.
- Remove the steak from the bag, pat dry and then sear for 90 seconds per side.
- Slice the steak against the grain and serve with the chimichurri sauce.