Mix together everything except the flat iron steaks in a medium bowl, then pour the mixture into a gallon-sized Ziploc bag.

Add the steaks and turn the steaks over inside the bag to coat it with the marinade. Try to arrange the steaks in a single layer.

Fill your sous vide pot (I use a large pasta pot) with water and attach your sous vide machine. Gently lower the Ziploc bag into the water and slowly seal the bag, making sure there are no air bubbles in the bag.

Set the temperature of your sous vide at 131 degrees Fahrenheit (55 Celsius) and cook for 5 hours.

When the steaks are almost finished cooking, heat a skillet over medium-high heat with a drizzle of olive oil inside.

Remove the steaks from the bag and discard the marinade. Sear the steaks for about 3 minutes on each side, pressing down on them with a spatula to get a nice brown crust.

Slice the steaks across the grain and serve drizzled with olive oil and seasoned with more salt and pepper.