Step 1

To make the marinade, whisk together the balsamic vinegar, soy sauce or Worcestershire sauce, apple cider vinegar, minced garlic, salt, black pepper, and olive oil until well combined.

Step 2

Place the skirt steak into a ziplock bag, pour in the marinade, press out any excess air, and seal the bag.

Step 3

When you're ready to sous vide the steak, preheat the water bath to 129 F or to your desired temperature according to the recommended time and temperature chart.

Step 4

Submerge the bag into the sous vide bath and cook the steak for 2 to 4 hours, depending on your preferred level of doneness.

Step 5

Once the steak is done, remove it from the water bath and transfer it to a cutting board. Pat it dry with paper towels and discard any leftover marinade from the bag or container it was marinating in.

Step 6

To make the chimichurri sauce, add all of the ingredients into a blender or food processor and pulse until the mixture is smooth and well combined.

Step 7

Use tongs to transfer the steak to a preheated grill and cook over medium-high heat for 6 to 8 minutes on each side, or until it's cooked to your desired level of doneness.

Step 8

Once the steak is cooked, remove it from the skillet or grill and loosely cover it with aluminum foil. Allow it to rest for 5 minutes before slicing it against the grain.

Step 9

Drizzle with fleur de sel (optional) and season with the prepared chimichurri sauce. Serve and enjoy your perfectly cooked and seasoned sous vide skirt steak!