Prep the steak. Trim excess fat and slice the steak into thin strips against the grain.
Pat dry with paper towels—dry surfaces sear better.
Mix the marinade. In a large bowl, combine oil, fajita seasoning, lime juice, 1 teaspoon salt, and 1/2 teaspoon black pepper. Whisk to blend.
Toss and rest. Add steak strips, peppers, and onions to the bowl. Toss to coat evenly.
Let sit 15–30 minutes while you prep your base and toppings.
Preheat the air fryer. Set to 400°F (200°C) for 3–5 minutes. A hot basket helps with browning.
Cook the vegetables first. Arrange peppers and onions in a single layer in the basket. Air fry 7–9 minutes, shaking halfway, until edges are lightly charred and tender-crisp.
Transfer to a bowl and cover to keep warm.
Cook the steak. Add steak strips in a single layer (work in batches). Air fry at 400°F for 4–6 minutes, shaking or flipping once. Cook to your preferred doneness; thinner cuts cook fast.
Combine and finish. Return peppers and onions to the air fryer with the steak for 1 minute to warm and mingle flavors.
Squeeze over more lime and adjust salt if needed.
Build your bowls. Spoon rice or greens into bowls. Top with steak and veggies, beans, and your favorite toppings. Finish with a generous squeeze of lime and a sprinkle of cilantro.