Flank Steak with Herbed Salsa

⏲ ~8 min total · prep 4 · cook 4 · 4 servings

By the KFI Test Kitchen · Tested & approved by Jason Lieu, KFI recipe editor

Published Sep 15, 2026 · Updated Sep 15, 2026

Ingredients

• 1 (1 1/2 lb) flank steak
• 2 tsp kosher salt, divided
• 1/2 tsp coarsely ground black pepper
• 1 tbsp avocado oil
• 1 cup finely chopped fresh parsley
• 1/4 cup chopped fresh mint
• 2 tbsp capers, drained and roughly chopped
• 1 small shallot, minced (about 2 tbsp)
• 1 garlic clove, grated
• 1 lemon, zested and juiced (2 tbsp juice)
• 1/3 cup extra-virgin olive oil
• 1/4 tsp red pepper flakes

Instructions

1. Season the steak all over with 1 1/2 tsp of the salt and the pepper and let it stand at room temperature 30 minutes.
2. Meanwhile, stir the parsley, mint, capers, shallot, garlic, lemon zest, lemon juice, red pepper flakes, olive oil, and remaining 1/2 tsp salt together in a bowl; let it sit so the shallot mellows.
3. Heat the avocado oil in a 12-inch cast-iron skillet over high heat until it just begins to smoke.
4. Lay the steak in the pan and sear undisturbed 4 minutes, until deeply browned with a charred crust; flip and sear 3-4 minutes more, to 125-130°F for medium-rare.
5. Transfer the steak to a cutting board, tent loosely with foil, and rest 10 minutes; the internal temperature will climb to 135°F.
6. Slice the steak thin across the grain, on a sharp bias.
7. Shingle the slices on a platter and spoon the herbed salsa, with its oil, over the top.

Why this recipe works

• Three net carbs, no cooking beyond one pan At 3.0 net carbs a serving, the whole dish is steak, herbs, olive oil, and a lemon. One cast-iron skillet does the only cooking there is, in about eight minutes of actual heat.
• Char from a dry, screaming pan Flank steak needs hard, fast browning or it turns gray and chewy. Cast iron heated to the point where the oil begins to smoke builds the charred crust in 4 minutes a side that a lighter pan never manages.
• The salsa does double duty Parsley, mint, capers, and lemon wake up a lean cut, and the oil in the salsa becomes the pan sauce. Nothing else needs making.

Tips for making this recipe well

Salt 30 minutes ahead

The steak stands at room temperature with most of the salt for half an hour before cooking. That window seasons past the surface and takes the fridge chill off, so the interior cooks evenly in the short sear.

Make the salsa first

Stir it together before the pan goes on the heat, and the 10 minutes of standing mellows the raw shallot. The flavors settle into the oil instead of sitting on top of it.

Leave it alone for 4 minutes

The steak goes into the smoking pan and stays put until a deep brown crust forms. Moving it early tears the crust and steams the contact side. Trust the timer over the urge to peek.

Pull at 125, eat at 135

The steak comes off the heat at 125 to 130°F and climbs to about 135°F during the 10-minute rest. That is medium-rare flank at its most tender. Cooked further, it tightens up fast.

Slice against the grain, thin, on a bias

Find the direction the muscle fibers run and cut across them at a sharp angle. Thick or with-the-grain slices chew like rope no matter how the steak was cooked. This one step decides the texture.

Serving suggestions

Shingle the thin slices on a platter and spoon the salsa over with all of its oil, letting it run into the cuts. At 3.0 net carbs, the side question is easy: arugula, roasted broccoli, or cauliflower puree all fit under the number with room left. This eats well warm or at room temperature, which makes it a strong lunch packed for work or a platter left out while people graze. Save any extra salsa for eggs tomorrow.

Storage and meal prep

Refrigerate the sliced steak and the salsa in separate covered containers for 3 to 4 days. The herbs in the salsa darken within a day, but the flavor holds. Cold flank steak over greens with the salsa as dressing is the leftover worth assembling. Cooked steak freezes for 2 to 3 months; thaw overnight in the fridge and warm briefly in a hot pan, since flank turns dry when reheated long. Skip freezing the salsa.

Variations worth trying

• Hanger or skirt steak Either cut takes the same salt rest, sear, and salsa. Skirt cooks even faster, so start checking at 3 minutes per side.
• Oregano in the salsa Swap the mint for a tablespoon of dried oregano and the salsa moves toward a chimichurri shape. The capers and lemon keep it bright.
• Grill version A hot grill does the same job as the cast iron in roughly the same time per side. Pull at the same 125 to 130°F and rest the same 10 minutes.
• Over greens Skip the platter and lay the sliced steak straight over dressed arugula or romaine, salsa as the dressing. Same dish, fork-ready, no extra carbs to speak of.

Frequently asked questions

Can I cook it past medium-rare?

You can, and the recipe's 125 to 130°F pull is medium-rare territory by design. Food-safety guidance puts whole cuts of beef at 145°F with a rest, which lands around medium. Past medium, flank steak turns tough quickly, so if you prefer it done, slice it thinner.

Why did my steak turn gray instead of browned?

The pan was not hot enough, or the steak was crowded or wet. Cast iron needs several minutes until the oil begins to smoke. Work in one layer, one steak, and let the crust form before anything moves.

Can I make the salsa ahead?

Yes, up to a day ahead in the fridge. The shallot mellows further and the herbs darken a bit, but it eats well. Bring it back to room temperature and stir before spooning it over the steak.

Do I need to rest the steak?

Yes, the full 10 minutes under loose foil. The temperature climbs from about 128°F to 135°F in that window, and the juices settle into the meat instead of the cutting board. Cutting early wastes both.

What if I can't find flank steak?

Skirt or hanger steak takes the same approach with the same salsa. Both are thinner, so pull them earlier, closer to 3 minutes on the first side. Slice both across the grain as directed.

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