Marinated Flank Steak (AIP, Paleo, Whole30)

Flank steak is one of those cuts that feels like a splurge without actually being one. It’s lean but deeply steak-y, quick-cooking yet perfect for feeding a crowd, especially when it’s been soaking all day in a simple marinade of our favorite anti-inflammatory flavor heroes: coconut aminos, balsamic vinegar and plenty of garlic. The result is savory, caramelized steak with big flavor and minimal effort. It’s on the table in under 20 minutes.

And here’s the bonus: flank steak naturally tapers from thick to thin, which means one end cooks up rare while the other lands closer to medium. In our house, that solves the Team Rare versus Team Medium-Rare debate without the need to fire up a second pan.

How this recipe fits AIP, Paleo and Whole30

This marinated flank steak is fully compliant with AIP Core, AIP Modified, Paleo and Whole30. Instead of traditional soy sauce, the marinade uses coconut aminos for umami without soy or gluten. Paired with balsamic vinegar and fresh garlic, it’s built around whole, minimally processed ingredients. When possible, choose grass-fed and finished beef for the best flavor and quality.

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Whisk together the marinade: olive oil (or avocado oil, if you prefer), soy sauce, balsamic vinegar, garlic and salt. I like to grate the garlic or run it through a garlic press to get the most flavor out of each clove. A good rule of thumb for salting any meat is one teaspoon of Diamond Kosher Salt per pound. I’ve taken into consideration that the coconut aminos also bring a lot of salt to the party, so in the countless times I’ve made this recipe, one teaspoon of salt more often than not tends to do the trick. That said, give the marinade a taste and adjust the seasoning to your preference. Don’t hesitate to add an additional pinch or two of salt, especially if your flank steak is a full two pounds or more.

Place the flank steak in a resealable bag or a baking dish and pour the marinade over, tossing a few times to coat. Let the steak marinate for at least two hours or up to eight hours in the fridge. (Longer is fine, but you won’t improve the flavor of the steak much more, and after a while the vinegar and the acidity in the coconut aminos will start breaking down the fibers of the steak and can negatively impact the texture.) If you can, give the steak a turn every hour or so to make sure both sides get maximum exposure to the marinade.

When it’s time to cook, shake off the extra marinade from the steak and discard the leftover marinade. This is the time to use your largest skillet. Coat it generously with avocado oil, which works well because it has a neutral flavor and a high-smoke point. Flank steak can be a little tough and lean, so it’s most tender at rare or medium-rare. For rare, cook it for four minutes on each side, or until the internal temperature in the thickest part reaches 120°. Or five minutes on each side to reach an internal temperature of 125° for medium-rare.

Then, transfer the steak to a cutting board to rest for at least 10 minutes. Continue to check with an instant-read thermometer to monitor the temperature of the steak as it rests. It will come up in temp between five and seven degrees. It’s done resting as soon as the temperature holds or begins to decrease. Examine the steak to find the striations of the meat running lengthwise and cut against that grain — usually across the width of the steak — in very thin slices. This will make this somewhat-tough cut melt-in-your-mouth tender.

For a final garnish, toss handfuls of scallions over the steak and finish with flaky sea salt. The scallions will balance the deep, rich marinade with a fresh, oniony bite. We always have leftovers in our house, and it’s possible to gently warm them at a low temperature in the oven to reheat. But I tend to resist, and instead look forward to tossing cold or room temperature slices over salads for days.

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Marinated Flank Steak (AIP, Paleo, Whole30)

5 from 1 vote

A quick marinated flank steak made with coconut aminos, balsamic vinegar, garlic, and olive oil. Tender, deeply savory, and perfect for grilling or cast iron cooking in under 20 minutes.

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Prep Time:10 minutes mins

Cook Time:15 minutes mins

Marinating Time:8 hours hrs

Servings: 6 servings

Author: Christina Marche

Ingredients

• 1 flank steak, (1¾ to 2 pounds)
• 3 tbsp olive oil or avocado oil, divided
• 2 tbsp coconut aminos
• 1 tbsp balsamic vinegar
• 2 cloves garlic, grated
• 1 tsp Kosher salt
• Scallions for garnish
• Flaky sea salt for garnish

Instructions

• Pat the flank steak dry with paper towels and place in a glass dish or a large resealable plastic bag.
• In a small bowl, whisk together 2 tablespoons of the oil, the coconut aminos, balsamic vinegar, garlic and salt. Pour over the steak and turn to coat. Cover the baking dish with plastic wrap or seal the bag and refrigerate for at least 2 hours, or up to 8 hours.
• Heat a very large skillet or cast iron pan over medium-high heat on the stovetop. Add a tablespoon of oil, then add the steak. Discard the marinade.
• Cook the steak to an internal temperature of 120° before resting for rare (or 4 minutes per side), and 125° before resting for medium-rare (or 5 minutes per side). Alternatively, place the steak directly on the grates of on an outdoor grill and follow the same temperature and time guidelines.
• Transfer the steak to a cutting board and rest for around 10 minutes, or until the internal temperature stops rising.
• Slice the steak against the grain and season with flaky sea salt and handfuls of scallions.

Course: Main Course

Cuisine: AIP, AIP Modified, Paleo, Whole30