Go Back
+ servings
Sous Vide Flat Iron Steak sliced over frites

Sous Vide Flat Iron Steak

This flat iron comes out perfect with a gentle sous vide cook before a finish on hot cast iron to lock-in that beef flavor and the kiss of Creole heat.
Course Main Course
Cuisine American
Prep Time 6 hours 10 minutes
Cook Time 1 hour 15 minutes
Resting Time 10 minutes
Servings 8
Calories 380kcal


  • Vacuum Sealer
  • Food Safe Bag
  • Sous Vide Machine


  • 1 2-3 lbs flat iron steak
  • 1 cup Tony Chachere’s Pourable Steakhouse Marinade
  • 3 tbsp Tony Chachere’s Original Creole Seasoning
  • 2 tbs butter


Marinate the Steak:

  • Pour the marinade over the steak for 6 to 8 hours before cooking. Discard the marinade.

Prep the Sous Vide:

  • Prep your sous vide machine according to the manufacturers’ directions for 125 degrees F.

Prep the Flat Iron:

  • Pat the flat iron dry and rub with a liberal coating of 2 tbsp Tony Chachere’s Original Creole Seasoning all over.

Sous Vide:

  • Place the flat iron in a food-safe bag and seal so there are no air pockets.
  • Submerge the now sealed steak in the water and set the timer for 1 hour.
  • When the flat iron has reached 125 degrees in the sous vide and is done, remove from the water and carefully remove the steak from the bag, reserving the juices.


  • Heat a cast-iron skillet over medium-high heat.
  • Add butter and swirl to coat the pan.
  • Sprinkle the remaining tablespoon of Tony Chachere’s seasoning over the steak and gently place into the pan. There will be a sizzle.
  • Sear on both sides until brown, 3 to 5 minutes, rotating and basting in butter as needed to form a good crust on all sides.
  • Use caution and an instant-read thermometer to not cook the steak past 135 degrees for rare.


  • Once the steak has rested a proper 10 minutes, slice in ⅛ to ¼” inch slices on a bias against the grain to serve.


  • If you would like to cook the steak to medium or beyond, adjust the temperature of the sous vide to reflect your desired temp, minus 5 to 10 degrees. The final sear will finish the last 5 to 10 degrees of cooking for your steak to temp just where you want it.
  • Leftovers can be stored wrapped tightly in foil and in the fridge for up to 3 days.
  • Reheat by rolling thin slices in a preheated skillet with a touch of oil or butter. Or re-heat slices under the broiler for a minute or two.
  • If you don’t have Tony Chachere’s Steakhouse Marinade on hand, try their Italian dressing instead! Different flavors but both options are great!


Serving: 1g | Calories: 380kcal | Carbohydrates: 11g | Protein: 34g | Fat: 21g | Saturated Fat: 9g | Cholesterol: 120mg | Sodium: 710mg | Potassium: 580mg | Fiber: 1g | Sugar: 8g | Vitamin A: 869IU | Vitamin C: 1mg | Calcium: 13mg | Iron: 4mg