Flat Iron Steak Fajitas

Prepare steak by placing it in a dish, then sprinkle 1 teaspoon cumin, 1 teaspoon oregano, ½ teaspoon chili powder, ¼ teaspoon salt, and 1 Tablespoon lime juice all over top of steak. Using tongs flip steak over and get some of the seasoning on the other side. Cover with lid and set aside for at least 10 minutes. Up to 12 hours.
While steak is marinating, slice ½ whole yellow onion and ½ whole red bell pepper. Heat cast iron skillet over medium heat. Once skillet is hot, add 1 Tablespoon neutral oil, then onion and pepper, ¼ teaspoon salt, and 1 teaspoon minced garlic. Stir occasionally and cook until onions are translucent, about 5-8 minutes. Remove from skillet.
Add remaining 1 Tablespoon neutral oil, once shimmering add flat iron steak. Cook for 5 minutes, then flip and cook the 2nd side for 5 minutes. Check doneness by inserting a thermometer into the center of the steak. It's done once the temperature reaches 145 degrees F. Remove from pan and let stand for about 5 minutes. Prepare tortillas and other toppings while steak is resting.
Cut steak against the grain. To determine where the grain is, look for the distinct strips of meat/lines on the steak. Cut perpendicular to those strips/against the grain. Serve hot with peppers, onions and tortillas. (optional toppings: salsa, guacamole, cheese, cilantro, corn, other sauteed vegetables)