Combine fajita seasoning in a small bowl and set aside.
Pour ¼ cup olive oil, ⅓ cup orange juice, juice of 2 limes, and 2 tablespoons of fajita seasoning into a medium-sized bowl and whisk to combine.
Add chicken to a resealable plastic bag with the marinade. Gently massage to coat completely, seal, and set in the refrigerator for at least 1 hour.
Whisk together sour cream, 2 tablespoons chili powder, and 3 teaspoons cumin together for the dressing. Add salt and lime juice to taste. Store in a sealed container in the refrigerator until ready to use.
Heat an outdoor grill or a grill pan oven medium-high heat. Cook chicken about 4 minutes per side or until internal temperature registers 165. Transfer to a plate and tent loosely with foil. Let cool at least 5-10 minutes before slicing.
Meanwhile, heat a couple tablespoons of olive oil in a cast iron skillet. Add onion and bell peppers. Sprinkle with 1 tablespoon of fajita seasoning and saute over medium-high heat until softened to your liking; about 4-5 minutes. Add corn and saute until corn is heated through. Juice a lime over the veggies, remove from heat and set aside to cool.
In a large mixing bowl, toss lettuce with the dressing. I recommend starting with half of the dressing, then add more to your liking. Or, serve on the side.
Divide salad into bowls. Slice chicken and divide chicken and vegetables evenly among the salad bowls.
Serve with lime wedges.
This recipe makes 4 generous portions of meal-sized salad. You could easily get 6 portions by using more lettuce. You can serve these in tortillas or over rice if you aren't a salad fan.