o prepare the marinade, combine all ingredients together into a medium bowl and stir to combine. Set aside.
Place the steak into a freezer bag and pour the marinade on top. Seal the bag tightly and turn several times to ensure the steak is evenly coated. Marinate at room temperature for at least 30 minutes (but less than 2 hours) or place in the refrigerator overnight.
Tip: If marinating the steak in the refrigerator, allow time for the steak to come to room temperature, approximately 20-30 minutes, before cooking.
Combine the tomatoes, one tablespoon fresh cilantro, red onion, and two tablespoons fresh lime juice in a bowl. Season with salt and black pepper, to taste, and stir to combine. Set aside.
To prevent browning, toss the chopped avocado with the remaining lime juice in a small bowl and set aside.
Heat a large cast iron skillet over medium-high heat. Remove the steak from the marinade and let excess liquid drip off before placing in the hot skillet. Sear for 3-4 minutes per side for medium-rare, or until the meat reaches the desired level of doneness.
Remove from heat and allow steak to rest 5 minutes before thinly slicing it against the grain. Serve immediately with the seasoned tomatoes, diced avocado, sliced radishes, lime wedges, and the remaining fresh cilantro. Top with sliced jalapeño and Cotija cheese. Offer guacamole, gluten-free tortillas, and/or lettuce wraps on the side, if desired. Enjoy!
Skirt and flank steak are two of the most popular cuts of meat used to prepare this dish. Both are great choices for marinades and a quick sear over high heat. The key to success with either option is to thinly slice the meat against the grain, or perpendicular to the long striations that run through the cut of meat, before serving.