In a medium bowl, whisk together olive oil, lime juice, and taco seasoning. Add chicken breasts and toss to coat. Cover and marinate for at least 1 hour or up to 8 hours.
Heat a cast iron skillet over medium-high heat. Cook chicken for 6–7 minutes per side, or until fully cooked. Rest for 5 minutes, then chop into 1-inch pieces.
In a small bowl, whisk together ranch, taco seasoning, cilantro, and lime juice until smooth. Adjust taco seasoning to taste.
Divide romaine between bowls. Top with cooked, chopped chicken, corn, black beans, tomatoes, red onion, and cheese.
Drizzle with Cilantro Lime Ranch and top with Fritos and fresh cilantro. Serve immediately and enjoy!