Description
These flank steak fajitas are fast, flavorful, and easy to pull together on a busy night. Instead of marinating the steak ahead of time, this recipe uses a reverse marinade — the steak is seared first, then rested in a bright lime-garlic mixture while it finishes cooking. This prevents burning, saves time, and keeps the steak juicy and tender.
Note: Rest time is about 10 minutes, which brings the total time to roughly 40 minutes from start to finish.
Ingredients
For the steak
- 1 1/2 pounds flank steak (anywhere from 1-2 pounds)
- Kosher salt or fine grain sea salt
- Freshly ground black pepper
- Avocado oil or another high-heat oil, for searing
Reverse marinade
- 3 tablespoons fresh lime juice (from about 2 large limes), plus more for serving
- 2 cloves garlic, grated or pressed
- 2 tablespoons extra-virgin olive oil
- 1 teaspoon ground cumin
- 1/2 teaspoon sea salt
- freshly ground black pepper
For the fajitas
- 1 large yellow onion, sliced
- 1 red bell pepper, sliced
- 1 green bell pepper, sliced
- 1 clove garlic, minced, pressed or grated
For serving
- Taco-size flour tortillas (or tortillas of choice)
- Optional: avocado, sliced or mashed
- Optional: chopped fresh cilantro
Instructions
- Season the steak & bring to room temperature: Generously season both sides of the flank steak with kosher salt.
- If you have time, let it sit at room temperature for 30–60 minutes to help it cook more evenly (this step is helpful but optional).
- Cut the steak into sections: If the flank steak is long or uneven in thickness, cut it into 3–4 shorter pieces. This helps it cook more evenly and a bit faster.
- Make the reverse marinade & prep vegetables: In a small bowl, combine the lime juice, grated garlic, olive oil, cumin, sea salt, and a few spins of black pepper. Set aside. Slice the onion and bell peppers.
- Cook the steak: Pat the steak dry with paper towels. Heat a large skillet (12-inch if possible) over medium-high heat until hot. Add a generous glug of avocado oil and sear the steak for 3–5 minutes per side, until well browned on the outside and still pink in the center.
- If the pan is smoking heavily or the steak needs more time, reduce the heat to medium and continue cooking to your desired doneness (about 135–140°F for pink, medium).
- Reverse marinate & rest: Transfer the hot steak immediately to a shallow bowl or dish. Pour the marinade over the steak and tent loosely with foil. Let rest for 10 minutes while the steak absorbs the marinade and finishes cooking. Warm the tortillas if needed.
- Cook the peppers and onions: While the steak rests, return the skillet to medium heat and add another splash of oil if needed. Add the sliced onions and peppers and cook until softened, about 7–8 minutes. A few minutes in, add a splash of water to deglaze the pan. About 5 minutes into cooking, add the garlic, ¼ teaspoon salt, and black pepper. Cook just until fragrant, 1–2 minutes, then turn off the heat. Adjust seasoning to taste.
- Slice & combine: Slice the rested steak against the grain into bite-sized pieces. Add it back to the pan with the peppers and onions (off the heat) to keep warm.
- Serve: Serve immediately with warm tortillas. Let everyone build their own fajitas — avocado first, then steak and vegetables, finished with cilantro if using.
Notes
Cooking flank steak over medium-high heat gives you the best sear without overcooking, adjust the cooking temp as needed
Always slice flank steak against the grain for the most tender texture and let it rest at least 10 minutes
This recipe works well for casual entertaining — I often bring the hot skillet to the table (carefully) and let everyone build their own fajitas
Leftovers keep well for up to 3 days and reheat nicely in a skillet