Marinate the steak: Add the oil, lime juice, chili powder, salt, cumin, oregano, garlic powder, and onion powder, to a large plastic bag. Use your hands to agitate the bag until all of these ingredients are mixed together. Add the steak to the bag and mix it with the marinade. Let this marinate in your fridge for at least 1 hour or up to 24 hours.
Grill the steak: Preheat your grill to high. Once hot take the steak out of the marinade and place each piece on the grill. Let the steaks grill on one side for roughly 3 to 5 minutes, then flip them over and let them grill for an additional 3 to 5 minutes. This should get you a steak in the medium-rare to medium range. If you would like your steak to be a little more well done then simply cook for an additional minute or two on each side. Once cooked take the steaks off of the grill, tent them with aluminum foil, and let them rest for at least 10 minutes.
Cook onions and bell peppers: While the steak is resting let’s cook the onion and bell peppers. Get out a large skillet or pan (preferably cast iron) and pour 1 tablespoon of oil into it. Place this over high heat and once hot toss in the sliced onion and peppers. Sautee these in the oil for 8 to 10 minutes or until they are softened, golden in color, and have slight char marks.
Cut Steak: Once the steak has rested it’s time to cut it. But you want to make sure that you cut against the grain. So first find the way that the lines are going in each steak. Then cut perpendicular to those lines in thin strips. If you want to you can place the cut steak in with the bell peppers and onion for serving in the pan/skillet.
Let everyone assemble their own steak fajitas by placing some steak, onion, bell peppers, and whatever additional ingredients they like on some warm flour tortillas. Enjoy!