Combine Cilantro Lime Sauce: add ingredients to a small food processor. Blend until smooth. Taste and add additional cilantro, lime or salt - as needed! Cover and place in the refrigerator until serving. 

Prepare Steak: Pat steak dry with clean paper towels. Season with salt and pepper - pressing the salt and pepper into the meat. Place steak in a large reusable silicone bag or glass baking dish and set aside.

Marinate Steak: Add olive oil, fresh lime juice, lime zest, chili powder, cumin, garlic, soy sauce, kosher salt and fresh cilantro (if using) into a small mixing bowl. Whisk until well combined. Pour the marinade over the steak, ensuring it is fully coated. Seal and place in the refrigerator for 30 minutes or more.

Cook Steak: Bring a large cast iron skillet to medium-high heat. Add a oil, swirl to coat the pan. Remove flank steak from marinade letting excess marinade drip off the steak; discard marinade. Place steak in the pan and sear 3-4 minutes per side. Take internal temperature and then cook 1-2 minutes per side until the internal temperature towards the thickest part of the steak reaches 130-132 degrees F. for a medium-rare finish (use an internal meat thermometer for accuracy) - during the cooking process turn down the heat, as-needed, if your skillet really gets hot and/or add a little extra oil if the pan is dry - to avoid burning. Remove from skillet and let the meat rest on a cutting board for 10 minutes while you cook the veggies. 

Cook Veggies: Keeping pan at medium-high heat add 2-3 tablespoons of chicken broth to deglaze the pan - use a spatula to scrape up the bits from the bottom of the pan. Add garlic and move around pan until it becomes fragrant, approx. 1 minute. Add onion, bell peppers and the fajita seasoning. Stir to combine.  Add additional broth or olive oil to pan if you feel it is getting a bit dry. 

Finish Veggies: Sauté for approx. 10-15 minutes or until the peppers have reached your desired doneness (cook shorter for a more firm, but tender pepper - longer for a softer pepper). Taste and add any additional salt or pepper, to taste.

Serve: Slice the steak against the grain into thin slices and serve on warm tortillas with the fajita veggies, cilantro lime sauce and any other toppings you desire!